380 Journal of Agricultural Research voi. xxii, no. s 



high eosinophilia is commonly present. An increase in the number of 

 eosinophile leucocytes has also been observed, although not as regularly, 

 in cases of infestation with species of Ascaris, Oxyuris, Strongyloides, 

 and other nematodes. Similar conditions have also been encountered in 

 cases of infestation with Taenia solium, T. saginata, Fasciola hepatica, 

 Clonorchis sinensis, and other cestodes and trematodes. As a matter of 

 fact, eosinophilia is so commonly associated with parasitic infestation 

 tliat the finding of a high eosinophile content in the peripheral blood is 

 generally considered as presumptive evidence of parasitic infection. In 

 a recent extensive review of the literature on the subject of eosinophilia, 

 Schwarz {191 4) states that an increase in the number of eosinophile 

 leucocytes in the peripheral circulation in cases of parasitic infestation is, 

 from an etiological viewpoint, the most clear-cut illustration of general 

 eosinophilia.^ 



Aside from the cellular inmiunity reactions, as shown by the increase 

 in the number of eosinophile leucocytes in the blood in cases of infesta- 

 tions with parasitic worms, there appears to be evidence of a humoral 

 immunity as well. In the case of hydatid (Echinococcus) disease of man 

 and animals, it has been shown by a number of investigators that specific 

 antibodies are present in the blood of the host, demonstrable by the 

 technic of complement fixation and precipitate formation. That such 

 immunity reactions are not limited to hydatid disease is the opinion of 

 certain investigators, who support their views by experimental evidence 

 which shows that specific antibodies are also present in cases of infesta- 

 tions with species of Ascaris, Fasciola, Schistosoma, and other parasitic 

 worms. ^ 



The facts cited in the preceding paragraphs appear to indicate that 

 hosts harboring parasitic worms develop typical defense or "immunity" 

 reactions to the absorption of foreign and presumably toxic substances 

 of parasitic origin. A logical corollary to the study of the serological 

 reaction of animals to secretions of parasitic worms is the study of the 

 secretions themselves with reference to their chemical and physiological 

 properties. This subject has recently received considerable attention 

 in studies on the causes of pernicious or infectious anemia of horses, a 

 disease of unknown etiology, which Seyderhelm and Seyderhelm (1914) 

 attribute to a secretory product of an internal parasite (the larvae of 

 Gastrophilus) . Although the assumption of the Seyderhelms has not been 

 confirmed, numerous experiments by diff'erent investigators have shown 

 that injection into animals of extracts of various parasitic Avorms may 

 lead to serious consequences, frequently terminating in death. Despite 

 the fact that these experiments are in a general way confirmatory of the 

 work of earlier investigators on the physiological effects of extracts of 



• " Die Vermehrung der a-Zellen in peripheren Blut bei Anwesenheit von Parasiten aus dem Stamme 

 der Wiirmer ist vielleicht die atiologisch am meisten klargestellte Form der allgemeinen Eosinophi'ie " 

 ' References to and a summary of this phase of the subject may be found in an article by G. Ghedini. 



