354 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1952 



Stiles, who followed Curtice as the parasitologist of the Bureau of 

 Animal Industry, brought to bear on his investigations a wide knowl- 

 edge of zoology and parasitology, together with a strong bent toward 

 preparing comprehensive studies and reviews of the morphology, 

 classification, and taxonomy of parasites of all sorts, including ar- 

 thropods. Independently and in collaboration with Hassall, he con- 

 tributed extensively to our knowledge of the cestodes of ruminants 

 and of related tapeworms of rabbits and hares, parasites of importance 

 in the inspection of meats, nematode parasites of ruminants, and re- 

 lated problems in parasitology. Stiles also was one of the earliest 

 workers to investigate verminous diseases of ruminants, which he 

 found to be associated principally with stomach worms and, to a lesser 

 extent, with other helminths. 



Ransom, who succeeded Stiles in 1903, resumed the studies of rumi- 

 nant parasites begun by Curtice 15 years earlier, limiting his inves- 

 tigations to the nematodes, but extending them to include the 

 roundworms of all the domestic ruminants. With the painstaking 

 precision which characterized his scientific work, Ransom showed 

 that the nematode fauna of ruminants in this country was richer than 

 his predecessors had recognized or suspected. He established, more- 

 over, sound and concise morphological criteria for the identification 

 of the genera and species involved. In his classic study of the life 

 history of the stomach worm, Haemonchus contortus, and of other 

 nematodes of ruminants, he determined that there was a pattern of 

 larval development and behavior, which has since been found to fit, 

 in a general way, the strongylid nematodes of herbivorous animals as 

 a whole. Ransom's investigations of ruminant parasites were brought 

 together in a monograph on the nematodes parasitic in the alimentary 

 tract of cattle, sheep, and other ruminants. Though this study was 

 published in 1911, it is still a useful and prized possession of livestock 

 parasitologists the world over, and in demand even today. 



INVESTIGATIONS OF ANTHELMINTICS 



Some years ago a pharmacologist in one of our leading medical 

 schools called attention to the fact that most of the anthelmintics then 

 known were derived from plants. He even speculated that this might 

 indicate a fundamental antagonism between animals and plants, the 

 one group being capable of producing substances that are more or 

 less injurious to the other. That most of the older anthelmintics were 

 of plant origin is evident from the mere enumeration of such sub- 

 stances as turpentine, areca nut, thymol, kamala, chenopodium, male 

 fern, and santonin, among others. 



In 1918 Hall and Foster published the results of an experiment in- 

 volving most of the then known veterinary anthelmintics, and con- 



