40 THE UNIVERSITY OF OKLAHOMA 



almost an)- organ in the bod)'. The ascarids are among the largest 

 of the group and nearlj' every species of animal has its special 

 \ariety. The human species, Ascaris Iiimbricoidcs, is now consid- 

 ered as identical with A. sniuii of the pig. The adults live in the 

 intestine but the larval stages cause many systemic disorders, espe- 

 cially of the lungs. It is known that some of the lung symptoms 

 manifested along v.-ith "worms" in children are due to larval as- 

 carids as they migrate to the lungs during a part of their life 

 cycle. In pigs man)^ of the cases of "thumps" are caused by larval 

 ascarids during their course of migration from the intestine, through 

 the limgs, windpipe, pharynx and dov/n the esophagus a second 

 time to the intestine where they grow to maturity. It is agreed 

 that ascarids of other animals go through the same course of mi- 

 gration. 



Human hook worms {A^ecator amcricaniis) are present in some 

 localities. Their prevalence may be ascertained from the fact 

 that approximately 6% of the men in the army camps from Okla- 

 lioir.a and Texas were infested. Verj^ few dogs in the vicinity of 

 Stillwater are free from hookv/orms (Anc'ystoiita cani>ntiii). Many 

 cats also harbour them. Sliecp and cattle also have another species. 



Children arc rather commonly infested with the pin worm 

 (O.ryurus T'cniiicularis ) . Species of Oxyitnis also infest horses 

 and cattle. The stomacli worm (Haeinonchus contortus) is very 

 (lestructi\e to cattle, sheep and goats. Various species of lung 

 worms attack sheep, cattle, horses and hogs and all are more or 

 Ics:; 'if economic importance to the live stock industry. Numerous 

 i^ihi-r -.pcc:es of rotmd vcorms attack man and his domesticated 

 animals so that this group of parasites is the most important from 

 the economic standpoin.t. 



Insects and Arachnids 



We ]ia\'e numerous tj-pes of lice, mites anrl fleas, which live 

 on tile exter;ijr i:)f man and animals. Certain insects are free living 

 as adults but their larvae are parasitic. We may mention the horse 

 liot-f!y. the ox-warble fly or "h.eel fly" of cattle, and the nose-fly 

 or gad fly of sheep. These are of extreme economic importance, 

 especially the nose-fly of sheep. The larvae live in the nostrils 

 and frontal sinuses of sheep and often cause very serious losses. 



Just a word might be said in regard to the numiier of parasites 

 that may be present in an individual animal and the degree ,of in- 

 festation in a group of animals. The writer has removed 3120 

 stomach worms, 319 hook v^'orrns, 150 nodular worms, and 31 

 tape worms from a single lamb. More than 5000 'worms of sev- 

 eral species were taken from one horse. A bull dog yielded 355 



