382 Journal of Agricultural Research voi. xxii.no. s 



the ether-soluble fraction left a fraction entirely devoid of hemolytic activity. The 

 ether-soluble fraction was then freed from its lecithin and cholestrin content without 

 injuring its hemolytic activity. In the remaining ether fraction (freed from lecithin 

 an'd cholestcrin) I^aust and Tallqvist identified tlu-ee fatty acids, namely, paln:itic, 

 stearic, and oleic acids. The first two substances did not exhibit any hemolytic 

 properties, whereas oleic acid was found to be markedly hemolytic. These investi- 

 gators therefore concluded that oleic acid is the active principle of Diphyllobothrium 

 hemolysin. 



In a later paper Faust {1908) records the results of experiments on the effects of oleic 

 acid on dogs when introduced per os. In brief, this investigator concluded that pro- 

 Icftiged feeding of oleic acid to dogs produced anemia in the latter, as evidenced by a 

 reduction in the number of red blood corpuscles. Beumer {igig), however, has 

 found, on the contraiy, that animals may be fed daily with considerable quantities of 

 oleic acid for long periods without permanent ill effects, and has failed to substantiate 

 the harmfulness of oleic acid. 



In this connection it is of interest to recall the experiments of Dascotte (cited by 

 Weinberg, 1912), who states that extracts of Taenia solium and T. saginata, cestodes 

 parasitic in man, dissolve human red blood corpuscles. Dascotte found, moreover, 

 that the hemolysin from these parasites is soluble in alcohol and resistant to heat at 

 temperatures of 100° to 120° C. Calamida {igoi) found that extracts of two species of 

 cestodes from carnivores {Dipylidiuvi canimim and Multiccps muUiceps) are hemolytic 

 to the red blood corpuscles of rabbits and guinea pigs and that the hemolysin goes 

 through the pores of a Berkefeld filter. According to Weinberg {igoy), physiological 

 salt-solution extracts of two species of tapeworms parasitic in horses (Anoplocephala 

 plicata and A. perfoliata) have no deleterious effects on the blood corpuscles of the 

 horse. Tallqvist {igoy), on the other hand, denies the presence of hemolysins in ces- 

 todes other than Diphyllobothrium latum. He states that he worked with a number of 

 species, including T. saginata. He admits that he sometimes observed slight hemolytic 

 effects of extracts of these parasites but expresses the opinion that they are to be 

 ascribed to secondary degeneration products associated with acid formation. 



While Diphyllobothrium latum is capable of causing severe anemia in man, clinically 

 indistinguishable from pernicious anemia and, according to many investigators, differ- 

 ing from the former in one respect only, namely, by the disappearance of the symptoms 

 and recovery of the patient after expelling the parasite, there are numerous cases on 

 record in which the presence of D. latum in man was not accompanied by anemia. 

 In fact, grave blood disturbances in cases of D. latum infection are, according to the 

 observations on record , not as common as the incidence of infection with this tapeworm, 

 a fact which has given rise to considerable speculation as to the causes of the occasional 

 appearance of anemia in the course of infection witli this parasite. These speculations 

 will be referred to elsewhere in this paper. 



In contrast to the occasional appearimce of anemia in cases of infection with Diphyl- 

 lobothrium /atowinfections with hookworms (Necator and Ancylostoma) are generally 

 accompanied by severe anemia. That the causes of anemia in hookworm disease are 

 due to a toxin is a view which was adopted by a number of investigators on a purely 

 a priori basis, because the direct abstraction of blood by these parasites, even when 

 present in large numbers, fails to account for the severity of the clinical picture usually 

 present in such cases. This fact was recognized early in the study of the disease, and 

 led to the postulation of the "toxin theory." 



Luscana (iSgo) found that as a result of injecting rabbits with urine taken from 

 patients suffering from hookworm disetise, the animals developed symptoms of anemia. 

 It was not until 1905 , however, that the toxin theory received more direct experimental 

 support from Calmeftte and Breton. These investigators found that salt-solution ex- 

 tracts of the Old World hookworm of man (Ancylostoma duodenak) are hemolytic to the 

 red blood cells of man. Alessandrini (zpo^) had already foxmd by direct microscopic 



