138 



NA TURE 



[Decemulk 7, 1905 



PHYSIOLOGY AT THE BRITISH 

 ASSOCIATION. 

 "TTHE section of physiology concerned itself very largely 

 ■*■ with the consideration of questions which are of 

 practical importance to workers in South Africa at the 

 present time. Such diseases as scurvy, leprosy, and plague 

 offer problems which demand instant consideration, and in 

 some cases legislation. The treatment of these maladies 

 formed the subject-matter of papers by the medical officer 

 for Cape Colony and his staff. 



The diseases of cattle are at present of great importance 

 in South Africa ; they played a prominent part in the 

 proceedings, both at Cape Town and at Johannesburg. 

 The fate of the four colonies, but especially of Rhodesia, 

 is intimately bound up with their value for rearing horses, 

 cattle, sheep, and goats. In recent years, and more 

 especially since the importation of stock from all parts of 

 the world during and after the Transvaal war, several 

 forms of disease have attacked the domestic animals of 

 South Africa. The severity of these diseases may be 

 judged from the fact that 97 per cent, of the horses at 

 I'niUili died of horse-sickness in a recent epidemic. No 

 more pressing problems, therefore, than the cause and 

 prevention of stock diseases present themselves to the 

 students of pathology in South Africa. At Cape Town the 

 morning of August 17 was devoted to their consideration. 

 I wo important communications were given by Mr. 

 Hutcheon, principal veterinary surgeon for Cape Colony, 

 and Mr. Lounsbury, Government entomologist in Cape 

 Colony. Mr. Hutcheon's great experience of the subject, 

 extending as it does from a time when the parasitic nature 

 of these diseases was unknown, and his constant and 

 successful efforts to combat successive devastations, render 

 his communication especially valuable. In recent years Mr. 

 Lounsbury also has done a vast amount of first-class work 

 in connection with the habits and life-history of the various 

 forms of tick which act as intermediate hosts for the 

 piroplasmic organisms. At Johannesburg a very compre- 

 hensive paper on rinderpest was given by the Hon. George 

 Turner, and one of much interest on horse-sickness and 

 similar maladies by Dr. Theiler, principal veterinary 

 surgeon of the Transvaal. Colonel Bruce's presidential 

 address dealt also with stock diseases. 



The importance of South Africa as a health resort 

 occupied the entire sitting of August 16. Sir Lauder 

 Brunton opened a discussion upon the effect of climate 

 upon disease and upon health. Dr. Gregory and other 

 South African medical officials took part in this dis- 

 cussion. Results also of great scientific interest upon the 

 effect of high altitudes on health were given by Prof. Bohr, 

 of Copenhagen. Mr. Barcroft described the outcome of 

 recenl researches upon the production of heat in the in- 

 dividual organs of the body, and indicated the bearing 

 of these investigations upon the heat-formation of the 

 body under varying climatic and dietetic conditions. 



The morning of September 1 was devoted to purely 

 physiological topics. 



Some of the more important communications may be 

 summarised as follows : — 



August 16. — Discussion on the effect of climate upon 

 health. Sir T. Lauder Brunton, F.R.S., pointed out that 

 three primary points had to be thought of in considering 

 climate, its effect (1) on the human body ; (2) on the 

 organisms which give rise to disease ; (3) on the carriers 

 of disease. After a detailed investigation of the effects 

 of change of environment upon protoplasm, he showed that 

 for every cell there was an optimum degree of humidity 

 and of salinity ; but more important than these was the 

 optimum temperature. When the temperature of the body 

 fell below o,8°4, the vitality, not only of muscle, but of 

 every other tissue, became reduced. The amount of heat 

 produced depended upon the activity of the tissues ; the 

 loss of heat largely depended upon the environment 

 (especially the temperature and the humidity). The nature 

 of the soil greatly affected the humidity, but often patho- 

 logical conditions were put down to the climate which 

 were attributable in reality to the effect of the geological 

 structure of a locality upon its water supply ; for instance, 

 the constipation experienced by many persons at sea-side 

 resorts in the south of England was not due, as often 

 NO. 1884, VOL. J $] 



supposed, to the sea air, but to the calcareous water. 

 Electrical conditions were referred to, especially the observ- 

 ations of Wier Mitchell and Dexter in America. 



Dr. Gregory pointed to the prevalence of tuberculosis in 

 South Africa, of which 17 per thousand of the natives and 

 7 per thousand of the white population died annually. On 

 the other hand, scarlatina, small-pox, typhoid, and in- 

 fluenza existed in much milder forms than in Europe. 



Prof. Bohr, speaking of the effect of high altitudes upon 

 health, introduced the results of his most recent investi- 

 gations upon the invasion and evasion coefficients of 

 oxygen in contact with liquid surfaces, and used these 

 coefficients to calculate the minimum barometric pressure 

 which was consistent with adequate respiration. He 

 showed how compensation was carried out at low pressures, 

 which, however, were higher than the absolute possible 

 minimum. The full account of his investigations appears 

 in Nagel's " Text-book of Physiology " — article on 

 respiration — to which the reader is referred. 



Mr. Barcroft dealt with the heat production in the 

 organs of secretion and excretion, and showed that these 

 organs were responsible for a much greater share of the 

 heat produced in the body than was formerly supposed. 

 The following figures might be taken as representing our 

 present knowledge of the heat formation per gram per 

 minute of certain organs when at rest : — The submaxillary 

 gland, 02 calories; the kidney, 0-15 calories; skeletal 

 muscle, 0-02 calories. In climates, therefore, where the 

 opportunity for heat loss was small (e.g. hot-damp climates) 

 these organs should not be unduly taxed. 



Other speakers were Dr. A. J. Mitchell, Prof. Sims 

 Woodhead, Dr. Murray, and Prof. Halliburton, F.R.S. 



August 17. — Mr. Hutcheon, principal veterinary surgeon, 

 gave an historical account of the diseases which had 

 devastated the stock of South Africa — pleuropneumonia, 

 redwater, rinderpest, east coast fever, biliary fever, horse- 

 sickness, &'c. Of these, heartwater, rinderpest, and horse- 

 sickness were the results of ultramicroscopic blood- 

 parasites, whilst the redwater of cattle and the east coast 

 fever were definite piroplasmic diseases. Ticks were 

 responsible for the communication of heartwater, red- 

 water, and east coast fever ; horse-sickness was probably 

 communicated by a mosquito. Mr. Hutcheon went fully 

 into the means that were now taken for preventing these 

 diseases. In the cases of redwater, heartwater, and rinder- 

 pest inoculation had been successfully carried out. 



Mr. Hutcheon attributed the absence of horses in South 

 Africa to the fact that zebras took horse-sickness, but not 

 fatally, and thus the infection was kept alive. 



Mr. Chas. P. Lounsbury, Government entomologist for 

 Cape Colony, treated of ticks as a means of transmission 

 of disease. The main features in the economy of ticks 

 were lirst discussed. Amblyomma hebraeum is the tick 

 responsible for conducting the heartwater of goats, 

 sheep, and cattle. It therefore prevents the successful 

 farming of wooled sheep and Angora goats over a con- 

 siderable tract of the country. The tick becomes infected 

 at one stage of its life-cycle and communicates the disease 

 at another. The requisite condition of warmth is necessary 

 during the metamorphosis of the tick if the disease is to 

 be communicated. Sheep of the Persian breed take the 

 disease more mildly than other varieties, and the virus is 

 somewhat modified by passing through them. The progeny 

 of thr transmitting lick appears to be innocuous. Haemo- 

 physalis leachi is responsible for the communication of 

 canine piroplasmosis. Unlike Amblyomma hebraeum, this 

 tick only communicates the virus by means of adults which 

 are the progeny of infected females. The virus, therefore, 

 passes through the egg, and remains latent in the nymphal 

 and larval stages. 



African east coast fever is communicated, like heart- 

 water, by the nymphs or adults of ticks which have them- 

 selves fed upon a sick animal. Five species of the genus 

 Eurhipicephalus, viz. appendiculatus, nitens, evertsi, 

 simus, and capensis, have been proved to carry this disease. 



Other speakers in this discussion were Colonel Bruce, 

 F.R.S., Sir W. Hely-Hutchinson, Mr. Robertson, Prof. 

 Sims Woodhead, and Mr. Bowhill. 



August 18. — Dr. Gregory gave a comprehensive paper 

 recounting the deductions which he had been able to make 

 touching the nature of scurvy as it exists in South Africa. 



