Introduction
During the heroic age of Antarctic exploration, bacteriology was performed, or at least planned, on nine expeditions. Some is still quoted in recent publications on Antarctic bacteriology but some remained unpublished and is thus hardly known. My aim in this paper is to review the way that bacteriology was performed and the results in general terms.
Antarctic bacteriology in perspective
At the time of the heroic age expeditions, bacteriology was a new but rapidly developing science. Modern bacteriology can be said to have started in 1860 when Louis Pasteur discovered that fermentation and putrefaction were caused by organisms. The first demonstration of a disease caused by a bacterium (anthrax in sheep) occurred in 1863. Robert Koch discovered the life-cycle of anthrax in 1876 and over the next 15 years there was an explosion of discoveries. Firstly there were technical discoveries (oil immersion lens, solid culture medium for growing bacteria, the development of stains to show bacteria) and secondly numerous bacteria were discovered (including the organisms causing tuberculosis, leprosy, diphtheria, typhoid and gonorrhoea). Because of the association of bacteria with human disease, bacteriology was led by the medical profession (Foster Reference Foster1970). Initially ‘most bacterial work was performed in the corners of domestic rooms, doctors’ surgeries or in ‘microscope rooms’ in hospitals. . . . the expectation was that the microscope and culture plate would be used by doctors as often as the stethoscope and thermometer.’ An early microbiology textbook, Klein's Microorganisms and disease was first published in sections in The Practitioner (a journal aimed at general practitioners) in 1884 and gave details on the best types of microscope, preparation of specimens, best dyes and fixing agents and recipes for different culture media. Kings College London started a bacteriology course for students and doctors in 1886. (Warboys Reference Warboys2000: 216)
Although bacteriology continued to gain in importance, the enthusiasm for it to be performed by general practitioners and generalist hospital doctors wore off. There were technical demands in maintaining the equipment, reagents etc and its ‘practical value seemed meager compared to the time, effort and money they [general practitioners] would have to put in’ (Anon. 1886). By the end of the 1880s Warboys states that the days of the dabbler were numbered and that bacteriology had been taken on by pathologists (Warboys Reference Warboys2000: 216).
However, practical bacteriology was still being taught to doctors and medical students and this included non-clinical bacteriology with a medical textbook of the time describing nitrification and denitrification in the soil as well as the bacteriology of disease (Hiss and Zinsser 1919) and medical textbooks described how to study bacteriology of water and the soil (Hiss and Zinsser Reference Hiss and Zinsser1910: 665–680; Eyre Reference Eyre1915: 416–441, 470–478) and at least one describes the technique of obtaining water from different depths (Eyre Reference Eyre1915: 417–419).
The doctors who undertook bacteriology on these expeditions qualified between 1884 (R. Koettlitz) and 1910 (A.L. McLean and S.E. Jones) and they would have all been taught bacteriological techniques as students and may have been taught the bacteriological examination of water and soil. Thus they would have seen this as an extension to their medical role and not as a separate branch of science. However, by 1916 the forward to the first bacteriological journal said ‘the time has forever gone by when bacteriology can be regarded merely, or even chiefly, as the handmaid of medicine or pathology. It is no less the servant of agriculture, of industry, of sanitation and of household life’ (Sedgwick Reference Sedgwick1916).
Research aims
For the reasons above, bacteriology on expeditions was usually done by the doctor. The expeditions on which bacteriology was planned and the doctors concerned are shown in Table 1.
Table 1. Expeditions recorded as undertaking bacteriology
I have found no results from the Belgica expedition and the next five expeditions all overlapped and so their bacteriology was done independently and it was not possible for one expedition to plan their research based on that done by its predecessors although because it was written up at different times, it was possible for some authors to compare their results with those of others.
A.L. McLean's research was done later but he says that although four bacteriologists had done previous work, he only had access to the results of one of these before he left ‘owing to the exigencies of time’ (McLean Reference McLean1919: 6).
H. Gazert described the planned bacteriological work of the Gauss expedition (1901–1903) in an article in the Scottish Geographical Journal. He described the importance of bacteria in breaking down organic matter and its conversion into a form that would nourish plant life. Low temperatures partially hinder bacterial growth and he described the main aim of his bacteriology: ‘to what extent this destructive process goes on in the Frigid zone is the chief object of investigation of the bacteriologist of the expedition’. His main interest was in the bacteriology of the sea. In the Arctic, Levin had ‘found bacteria in sea water of −2° C, and . . . these bacteria performed all their functions, although quantitatively much weaker than in warmer surroundings’ (Gazert Reference Gazert1901: 470, 473).
The first intention was: ‘the germ life of sea water of different depths, of bottom samples, of the air, of the ice, of the pools on the ice, of the soil, and of the fresh water on land, must be studied as far as possible in the same locality in the different seasons of the year. The examination of anaerobic bacteria must not be neglected.’
More specifically he planned to investigate nitrifying and denitrifying bacteria. Nitrates, nitrites and ammonium salts are present in the sea both from the breakdown of organic material and after being washed into the sea from rivers. In addition there are nitrogen-fixing bacteria (nitrifyers) in the sea. It was known that plankton were more numerous in cold water and it was also thought that denitrifying bacteria were commoner in warm water. Gazert wanted to test the hypothesis that plankton were more common in cold waters because of the relative absence of denitrifying bacteria leading to an increase in nitrogen containing salts and thus nutrients. This was important because plankton sustains animal life in the oceans (Gazert Reference Gazert1901: 572–573).
In the Arctic, Levin had ‘found the intestines of several birds and seals absolutely sterile, nor could he detect bacteria by cultivation under the microscope. He correctly attached importance to this discovery, since the necessity for the presence of bacteria in the intestine has not been clearly demonstrated . . . It is therefore particularly interesting to find out whether there really exist in nature animals with no bacteria in their intestines . . . [so] observations of this kind . . . will be part of the bacteriological work done by the expedition’ (Gazert Reference Gazert1901). This explains why a history of Antarctic science says that ‘there was a preoccupation with plating out animal faeces’ (Fogg Reference Fogg2005: 348). Gazert planned to bring back live cultures.
W.S. Bruce presumably intended that bacteriology would be a major part of his research as he advertised for a bacteriologist (Anon. 1902) to accompany the Scotia expedition (1902–1904) and appointed J.H.H. Pirie, a recent medical graduate from Edinburgh. However Pirie was also experienced in geology and went to the Antarctic mainly as a geologist and admitted that: ‘extensive bacteriological investigations did not come into the programme of work undertaken on the Scotia. . .’ (Pirie Reference Pirie1912). He had very similar aims: ‘to see if bacteria were present in the alimentary tracts of Antarctic animals, as it has been maintained by some that they were absent from those of Arctic animals’ and to look at ‘the presence and nature of bacteria in the sea’ (Pirie Reference Pirie1904: 131). He later became a full-time bacteriologist who became well-known for his work on plague and his discovery of Listeria in South Africa.
Before the Discovery expedition, a book, The Antarctic manual for the use of the expedition of 1901, (Murray Reference Murray1901) was issued, containing plans for research on the expedition. Bacteriology is not mentioned. The idea for bacteriological research appears to have been Koettlitz's. When Sir Clements Markham wrote, offering him the job of medical officer and botanist, Koettlitz replied: ‘I am very willing to accept the post and to qualify myself to undertake the other duties you mention, with bacteriology, if such were considered expedient. . .’ (Koettlitz Reference Koettlitz1900).
The way in which his equipment was provided, also indicates that his research was not planned by a national scientific body: on 2 February 1901, a letter appeared in the Guy's Hospital Gazette:
Dear Sir, - I should feel obliged if you would make known . . . that Dr Koettlitz – an old Guy's man – is to be in charge of the bacteriological investigations which are to be undertaken in the forthcoming expedition to the Antarctic regions. I understand . . . that the available funds are . . . too small . . . It seems to me that . . . it would be an exceedingly nice thing if the laboratory were equipped by those who own Guy's as their alma mater. For this purpose about £100 would be needed. . . (Pakes Reference Pakes1901).
Like Gazert, Koettlitz was aware of the results of bacteriological research in the Arctic and, in particular noted that the intestines of most animals in the Arctic were sterile. He commented: ‘how much of interest may not be obtained by careful investigation at the opposite Polar area’ (Koettlitz Reference Koettlitz1901). Later, in a newspaper interview in New Zealand, he said that he planned to apply his bacteriology to the diseases of birds, seals, sea lions and the inhabitants of the oceans (Anon. 1901).
The bacteriology done on the Australasian Antarctic Expedition does not appear to have been one of the major scientific aims of the expedition as McLean's letter of appointment says ‘it is well for you to discuss matters with Welsh [Professor of Pathology, University of Sydney] and arrange for any particular work you may be able to execute in the special conditions of Antarctica’ (Mawson Reference Mawson1911). This was less than three months before the ship departed. McLean also mentions the names of others who assisted him including J.B. (later Sir John) Cleland, (McLean Reference McLean1919: 9) a distinguished Australian microbiologist, but it is uncertain as to whether they assisted with his research plans or with further study on his return to Australia.
McLean does not mention his research aims but it is clear from what he did, that his plans were very similar to the others. However he also did some clinical bacteriology in that he investigated the microbiology of seal wounds, pus from a boil, a whitlow and a dental abscess of expedition members. He brought back some live cultures for further study in Australia. He also investigated immunity and changes in normal bacterial flora over time. I will discuss these elsewhere. McLean's work formed the basis of a doctoral thesis (McLean Reference McLean1919).
Charcot had worked at the Pasteur Institute, a world-famous laboratory and his bacteriology seems to have been done in association with Nobel prizewinner I. Metchnikoff who worked at the institute, whose name is mentioned both in relation to the bacteriology of the Français expedition (Tsiklinsky Reference Tsiklinsky1908: 1) and as a collaborator in the research of the Pourquoi Pas? expedition (Muntz and Lainé Reference Müntz and Lainé1913a).
Charcot brought back live cultures of organisms for further identification on their return and some soil back to be examined. In France the microbiology was performed by Mlle Tsiklinsky (Tsiklinsky Reference Tsiklinsky1908).
Following the success of Charcot's first expedition (in all its aspects and not just bacteriology), he secured the support of the Académie des Sciences for a further expedition and they published instructions for the research that they felt should be done on that expedition (Institut de France, Académie des Sciences 1907). Roux, another famous bacteriologist and director of the Pasteur Institute wrote the microbiology section of the instructions (Roux Reference Roux1907) and advised that Charcot study the microbiology of the air, the sea, fresh water and the intestinal tracts of fish and animals. He also advised study of protozoa and parasites.
There was a sense of excitement about the planned bacteriological research. Mlle Tsiklinsky (Tsiklinsky Reference Tsiklinsky1908: 2) said that this was a study of bacteriology where man have never put his foot. Müntz (one of the founders of soil microbiology who proved that the nitrification of soil was a microbiological process) had written: ‘The study of the survival of soil organisms will be interesting . . . If, in these conditions [very low temperatures] one finds living organisms, there are two possibilities: either they are living organisms that have laid dormant for myriads of years or one has found species that have the ability to develop in conditions of temperature at which most life ceases (Müntz Reference Müntz1907). He had previously found nitrifying bacteria under a glacier in the Alps but felt that this might have come from wind-carried dust that had penetrated the glacier and he wanted to examine soil from beneath an Antarctic glacier as such earth would have been buried under ice for thousands of years and there was no wind-borne soil to contaminate it (Müntz and Lainé Reference Müntz and Lainé1913b).
That these were written in 1907 is surprising as, by that time, Ekelöf, Gazert and Pirie had already done research in this area and although some of it may not have been published, there was close collaboration between Antarctic scientists and this should have been known about. Even if they were unaware of this work, they would have known of Charcot's work from the Français expedition and this is not referred to. Charcot described himself as a bacteriologist (Charcot Reference Charcot and Walsh1978: 22) though on this voyage he seems to have been just a collector of specimens as he wrote ‘We brought back . . . a number of preparations and sealed tubes containing fecal matter, soil, etc., which will be studied from the point of view of bacteriology’ (Charcot Reference Charcot1911). The only publication of results that I am aware of was a sample of soil, examined for nitrifying bacteria which was collected by R. Godfroy rather than Charcot (Müntz and Lainé Reference Müntz and Lainé1913b).
Difficulties in doing bacteriological research
Gazert recognised the difficulties that would occur: ‘We will not attempt the investigation of the morphological relationships of the micro-organisms to the different media they are found in’ as it would be too difficult to get accurate results but this would be done on return with some pure cultures. In addition he said: ‘how far these are practicable on the voyage is certainly not easy to say’ and he identified limited room, stormy seas and accidents as problems. In addition: ‘the greatest enemy of the bacteriologist is mould. . .’ (Gazert Reference Gazert1901).
These expected difficulties did happen. Drygalski wrote that ‘Gazert's bacteriological work . . . was dogged by growths of mould that sprang up all over the ship, so it was hard to keep the culture bottles clear, while the chemical tests were confused by the fact that ammonia, nitrous and nitric acid reactions were spoilt by the presence of iron oxide that sometimes produced quite illusory results in bacteriological tests on bottom samples’ (Drygalski Reference Drygalski and Raraty1989: 81).
Pirie found that while he could make media for cultivation of denitrifying organisms and simple gelatin media, it was almost impossible to make agar media due to mould. In addition, necessary economy with fuel caused problems with the incubator so a warm corner of the engine room was used as an incubator. The resulting variations in temperature were not conducive to best results (Pirie Reference Pirie1912). Pirie brought back some cultures preserved in formalin and attempted to bring back some stained slides of bacteria but many of these were spoiled by mould.
As on all expeditions, McLean found that space was a limitation and, at sea, had problems with the ship rolling. He, too, had difficulties with fungal spores and found that gelatin culture media froze and split. His colleague S.E. Jones who was medical officer at the Australasian expedition's Western Base was also equipped to do bacteriologicy ‘but was forced to abandon any researches on account of his culture media becoming contaminated’ (McLean Reference McLean1919: 8). He also had other problems as for more than four months he was unable to do gram stains as stocks had been misplaced. ‘The boxes containing my stock of materials were buried in snow outside the Hut and were only accessible on the rare fine days, when they had to be dug out, opened and re-packed’ (McLean Reference McLean1919: 8).
A more severe disruption to research occurred to E. Ekelof when his ship, Antarctic, sank which meant that he was unable to do all his planned research into the bacteriology of sea water though he did contribute greatly to the study of the bacteriology of Antarctic soil.
Difficulties of another kind came from the collecting of specimens. As noted above, Müntz wanted to obtain soil from beneath a glacier but Godfroy found it impossible to get through the ice to collect a sample and had to make do with a sample of frozen mud retrieved from an iceberg (Müntz and Lainé Reference Müntz and Lainé1913b).
The doctors appear to have had three main reasons for going to the Antarctic: adventure, medicine and science, and bacteriology was not always given the top priority. On the Australasian expedition the research was mostly done during the winter as ‘in the summer of 1912 to 1913, most of us were away on long sledging journeys. . .’ (McLean Reference McLean1919: 9) and Koettlitz in his notes at one point says ‘(NB) Owing to departure upon sledge journey duty, the observation was interrupted for 6 weeks’ (Koettlitz Reference Koettlitz1904: 6).
E.L. Atkinson went to the Antarctic primarily as a parasitologist but was also equipped to do bacteriology. He undertook some bacteriology during the first winter (Atkinson Reference Atkinson1913) but most was planned to be done later. E.A.Wilson explained: ‘The bacteriology is postponed until nearer the time of departure as it is impossible to maintain cultures without loss of all characteristics over a lengthy period of time. They will, therefore, be collected at the last moment, and taken home at once’ (Wilson Reference Wilson and King1972: 188). This did not happen, presumably because of Scott's death and Atkinson having to take charge of the expedition with the added responsibilities of searching for Scott's party and the potential for having to search for the Northern party. His work was never published because, as Atkinson wrote: ‘Unfortunately only one season . . . could be utilised to work after this subject and the results have been correspondingly poor’ (Atkinson Reference Atkinson1913).
Equipment taken
The equipment required for bacteriology includes, sterilisers, incubators, glassware, culture media of various sorts and stains. This was, of necessity, basic. Atkinson took two incubators that could be heated either with an oil heater or acetylene (Atkinson Reference Atkinson1913). The Wellcome Library contains a full list of the chemicals and stains that he took (Anon. 1910).
Despite the support of the Pasteur Institute, Charcot's bacteriology on Français seems to have been under-funded as he says: ‘I set up a variety of bacteriological apparatus using a jam tin and a funnel to make a condenser. Using two biscuit tins placed one within the other, and covered with a suitable lid . . . I obtained a steriliser and propagator which, mounted on a wooden base . . . and heated by a variable number of small paraffin lamps of my own invention, was, I have to say, quite a success’ (Charcot Reference Charcot and Billinghurst2004: 77). He goes on to say ‘Although it might have been better to have had the resources and the experience which would have allowed us to take everything complete and ready made instead of having to improvise, for me at least, the ingenuity one had to call upon – especially when it was crowned with success – was not without a certain charm of its own’ (Charcot Reference Charcot and Billinghurst2004: 81). This type of improvisation was by no means uncommon as Charcot says: ‘All the manuals talk about the use of makeshift laboratories in warm countries. I could add a chapter about their use in cold countries’ (Charcot Reference Charcot and Billinghurst2004: 81).
Results
McLean (Reference McLean1919) summarises the work of Ekelöf, Gazert, Pirie and Charcot/Tsiklinsky and Pirie (Reference Pirie1912) compares his results with those of Ekelöf, Gazert and Charcot/Tsiklinsky. I have used these as my basis for discussing the research published in German and French.
It would seem that some bacteriology might have been done on the Belgica expedition as in a list of the expedition's future publications, the botanical and zoological results (Volume VI–IX) were to contain a section entitled ‘Bactéries de l'intéstin des animaux Antarctiques’ by J. Cantacuzéne (de Gerlache Reference De Gerlache1902: 298–299) a Romanian bacteriologist who, at the time, was working at the Pasteur Institute with Metchnikoff. However I have found no mention of bacteriology in the books of the expedition by A. de Gerlache (de Gerlache Reference De Gerlache and Raraty1998) R. Amundsen, (Decleir Reference Decleir1999) or F.A. Cook (Cook Reference Cook1980) and have also found no record of such scientific results being published. If samples were taken (probably by E. Racovitza, the naturalist, rather than by Cook) for microbiological investigation on return to Belgium, it would appear that for some reason, the results were never published.
Alimentary tract of Antarctic animals
Koettlitz (Koettlitz Reference Koettlitz1904) obtained cultures from penguin and seal intestines but his results were never published. However, some of his results were painted by E.A. Wilson (Figs 1, 2).
Figs. 1, 2. Paintings by E.A Wilson of bacterial cultures on the Discovery expedition. Printed by kind permission of the Natural History Museum (see Koettlitz Reference Koettlitz1904).
McLean says that ‘the bacteriological observers of four previous Antarctic expeditions [Ekelöf, Gazert, Pirie, Tsiklinsky] agree . . . that the intestinal canal of an Antarctic vertebrate is relatively sparse in bacteria’ and Pirie says that ‘in a number of instances they (the intestinal tracts) appear to be altogether sterile, or, at any events, any bacteria they may contain fail to grow on the ordinary, commonly used nutrient media.’
In seals bacteria were cultured from the large intestines of most varieties.
In penguins, Ekelöf was unable to obtain any bacteriological growth; Charcot managed to culture organisms but fewer than would be expected in temperate climates. McLean cultured bacteria from penguin guano.
Ekelöf obtained bacterial growth from skuas on two occasions but failed on other occasions and he also failed to culture organisms from any other bird. Pirie was able to culture organisms from the alimentary tracts of ten of 15 varieties of birds and McLean was only able to obtain cultures from five out of nine varieties of bird.
In fish, Charcot obtained bacterial growth, but less than would be expected in a temperate climate and McLean was also able to culture organisms from fish including one obtained from 1,700 fathoms (3,100 m).
All the above are the results of attempting to culture organisms but McLean did smears of intestinal contents and noted: ‘It is apparent . . . that bacteria were fairly numerous in almost every smear examined [of intestinal contents of mammals, birds and fish]’. It is therefore clear that bacteria exist in the alimentary tracts of these animals but they do not always grow in culture.
It has since been discovered that the reason for this is that phytoplankton and krill which form the diet of many of these animals, possess strong antibacterial activity. Penguin gastric contents and penguin flesh also have antibacterial activity, probably secondary to their diet. This antibacterial activity of phytoplankton and krill probably also explains a relatively low number of organisms in the Antarctic seas (Sieburth Reference Sieburth1959).
Air
Pirie found growth on plates left on the roof of his laboratory on board ship but this was probably contamination as he found no growth on plates exposed on the crow's nest of his ship for periods of up to 20 hours. Atkinson found no growth in air. Ekelöf, on land, found that he had to expose a Petri dish to air for two hours to obtain one colony on the plate.
Soil
The main research on soil microbiology was done by Ekelöf who examined 105 specimens and found that 88.5% contained bacteria but often needed incubation for six to eight days. He found 29 different bacteria and also what McLean calls ‘yeasts’ but he says that among these were three species of actinomyces (which are bacteria) and one that Ekelöf was unable to classify. The bacterial count was higher in summer and no bacteria were present in soil deeper than 20cm. Gazert found an anaerobic bacillus similar to Bacillus tetani (now called Clostridium tetani).
Müntz examined some earth found within an iceberg as representing earth that had not been exposed to air for perhaps thousands of years and found that it contained no nitrifying bacteria (Müntz and Lainé Reference Müntz and Lainé1913b). McLean found organisms, one of which matched an organism described by Ekelöf and others were similar. Tsinklinsky found five organisms in morainic mud but none correspond to McLean's organisms and this soil was probably contaminated by penguins and other birds.
This research was done at a very early stage in the history of soil microbiology and soil organisms had not been fully classified and systematised. McLean says that ‘the bacteria of Antarctic soil are prolific in number, and . . . a rich field of enquiry and speculation lies open to scientists of the future.’
Sea
Most samples of sea water grew organisms. From 25 cultures of sea water Tsiklinsky isolated five species of bacteria and two species of ‘yeast’. Unsurprisingly bacterial concentrations were higher nearer land but organisms were also obtained from the bottom and Gazert grew bacteria in 21 of 24 samples of bottom water. Pirie found a bacillus at 2,550 fathoms
Neither Pirie nor Gazert found any evidence of nitrifyers and Pirie concluded ‘that nitrifying organisms are not present in these waters, or that the media employed were not suitable for their growth’ (Pirie Reference Pirie1912: 147).
The theory that denitrifyers did not exist in the Antarctic was only partly true as although Pirie found ‘that the presence of organisms with denitrifying properties seems to be fairly constant in the surface waters’, the organisms seemed inactive as ‘judging from the results obtained in cultures kept at those constantly prevailing in that sea . . . it seems at least doubtful if much active denitrification can be carried on by bacteria in those waters’. He says that ‘Gazert records fairly similar conditions’ (Pirie Reference Pirie1912: 145).
Snow
Gazert was unable to culture bacteria from snow but Atkinson found a bacillus in snow as described by Scott: ‘Atkinson is pretty certain that he has isolated a very motile bacterium in the snow. . .’ (Scott Reference Scott and Jones2005: 191). Atkinson notes that initially he obtained no growth but grew a bacillus from freshly-fallen snow after a warm blizzard. McLean found bacteria, yeasts and protozoa in ice and grew bacteria from fallen snow and described this in Nature (McLean Reference McLean1918). Fig. 3 shows a cartoon of McLean searching for bacteria in snow.
Fig. 3. McLean searching for bacteria in the snow. Printed by kind permission of Mitchell Library. State Library of New South Wales (McLean Reference McLean1911–1918).
Clinical
Animal
Wilson says that the seals often had infected wounds, the results of injuries sustained while fighting or by attacks from killer whales (Wilson 1905). Young seals often had conjunctivitis. Koettlitz did microbiological investigations on conjunctivitis and infected wounds in seals. These results were never published.
McLean also investigated the bacteriology of wounds in Weddell seals (Leptonychotes weddellii). These wounds had been caused by attack by killer whales (Orcinus orci)and leopard seals (Hydrurga leptonyx) (known then as sea leopards). He found staphylococci, streptococci, a Gram-negative mycelium, Gram positive yeast-like bodies and Gram-negative bacilli.
Human
McLean was the only person to report microbiology of human infections in the Antarctic. Three members of Mawson's party developed whitlows which were opened. One of these grew Staphylococcus aureus, Streptococcus pyogenes and Staphylococcus albus. McLean goes on to say that Staphylococcus aureus was not present in the dust of the hut nor in pharyngeal or nasal swabs.
A boil grew Staphylococcus albus and a dental abscess grew Staphylococcus albus, Streptococcus pyogenes, Bacillus hoffmanni and diphtheroids. Bacillus hoffmanni is a diphtheroid (ie an organism similar in appearance to Corynebacterium diphtheriae, the organism that causes diphtheria)
In addition, McLean was interested in the changes in immunity that occurred in polar regions did some routine screening of nose and throat swabs in expedition members to observe changes over time. I will discuss this elsewhere.
