September S, 1905.] 



SCIENCE. 



299 



of fact, there are no horses, dogs or cattle 

 in the 'fly country.' In other protozoal 

 diseases, such as the Piroplasmata^ this ac- 

 quired immunity seems to come about fairly 

 readily. 



To sum up, then, the increase in our 

 knowledge of tsetse-fly disease during the 

 last ten years, we may say that we have 

 discovered the cause in the shape of the 

 small blood parasite Trypanosoma; we have 

 found that the reservoir of the disease exists 

 in the wild animals, and that we can blot 

 out this disease from any particular tract 

 of country by the simple expedient of de- 

 stroying or driving away the wild animals. 

 We still have no means of preventive in- 

 oculation or successful medicinal treatment 

 in this disease. 



2. Trypanosomiasis of Cattle. 



This disease seems to be widespread over 

 all South Africa. It can not be said to be 

 of much practical importance, as the cattle 

 infected do not seem to be seriously affected 

 by it. It is caused by a species of trypano- 

 some remarkable for its large size, which 

 was discovered by Dr. Theiler some years 

 ago, and named T. theileri. 



Dr. Theiler states that it is conveyed from 

 animal to animal by the common horse-fly, 

 Hippahosca rufipes. 



This, then, is a short account of the 

 trypanosome diseases which aifect South 

 Africa. 



Of late years the tsetse-fly disease has 

 become of less practical importance to the 

 Transvaal, from which it has practically 

 disappeared. This is due to the disappear- 

 ance of the game, killed off by rinderpest; 

 but with the preservation and restoration 

 of the reserves with big game the disease 

 is certain to reappear. Why the fly should 

 disappear with the game is not known. 



D. Bruce. 



{To he continued.) 



EUROPEAN AND AMERICAN SCIENCE. 



One of the important accomplishments, 

 doubtless, of the International Congress of * 

 Arts and Science held in connection with 

 the exposition at St. Louis was, simply, the 

 bringing to this country of a large number 

 of learned men from other nations. Some 

 of these men had visited America before, 

 but many of them crossed the Atlantic last 

 autumn for the first time and viewed 

 Americans and American institutions with, 

 as it were, a virgin sense. A number of 

 those who made the trip have recorded their 

 impressions in addresses or journal-articles. 

 It would be a worthy task, should these 

 increase in number, to collect and to pub- 

 lish them together, for aside from the grati- 

 fication of the curiosity of seeing ourselves 

 as others see us, it could scarcely fail to be 

 instructive for us to study the observations 

 and comments of men of the high type of 

 those who were invited to the congress. 



Of the foreign scientists who attended 

 the St. Louis meeting and have given 

 public expression to their ideas of America, 

 one of the most distinguished and discern- ^ 

 ing is the professor of anatomy in the 

 University of Berlin. It was not Professor 

 Waldeyer 's first visit to America ; fond of 

 travel and widely-travelled as he is, it was 

 not for a man such as he to have left so , 

 long America unvisited. Moreover, an 

 omnivorous reader, Waldeyer is more or 

 less familiar with American literature; he 

 numbers, too, among his friends many 

 American scientists and literary men; in- 

 deed, many young biologists and anatomists 

 from America have, in part at least, re- 

 ceived their training in his laboratory. By 

 personal observation, by correspondence, 

 by reading and by multiple contact with 

 educated Americans, Professor Waldeyer 

 has had, more than most foreigners, op- 

 portunities for familiarizing himself with 

 American science and American thought. 



