308 THE BIOCHEMISTRY OF B VITAMINS 



nutrition of the Porifera and Coelenterata creates a great gap. The 

 economic importance of these phyla may soon, however, induce sufficient 

 effort into the study of this group of animals to overcome the experimental 

 difficulties inherent in the investigation of their nutrition. 



Regarding the Plathelminthes, studies on the nutrition of Planaria 

 maculata have shown that a heat-labile, ether-soluble fraction of liver 

 is required for growth, s and that a similar and possibly identical factor 

 is inactivated by egg white. Despite the conflicting nature of the descrip- 

 tions, there is some reason for believing the factor to be biotin. It has 

 been shown 9 that the number of tapeworms (Hymenolepis diminutia) 

 in rats on various vitamin-deficient diets varies broadly. Thiamine- 

 deficient rats have worm populations similar to those of normal rats, 

 whereas rats deficient in the "B complex" vitamins have reduced numbers 

 of worms. We shall see shortly that, by contrast, studies of parasitic 

 round worm infections in humans and rats show increased populations 

 of worms in malnutrition. 



The fish tapeworm, Diphyllobothrium latum, infects humans and causes 

 a macrocytic anemia differing from Addisonian pernicious anemia in that 

 spinal cord involvement is rare, gastric acid is seldom decreased, the 

 anemia is cured by removal of the worm, etc. Extracts or suspensions of 

 the worm are inactive, and considerable evidence suggests that the effect 

 produced may possibly be due to absorption by the worm of the anti- 

 pernicious anemia factor (vitamin Bi 2 ) in the host, in a manner similar 

 to that in which live yeast may deplete the intestinal tract of thiamine 

 (p. 291 ), 10 and produce the corresponding avitaminosis. One is caused 

 to wonder in passing whether a metabolic factor is involved in the pro- 

 duction of rat liver sarcoma by the flat worm Cysticercus. 11 



The nutrition of a number of round worms (Anguilla oxophilla, 1 ' 2 

 Neoplectana glaseri, 13 and Ancylostoma caninum 14 ) has been studied, 

 but never in such a manner as to indicate much with regard to their 

 B vitamin requirements. All require complex media (yeast autolysate- 

 peptone, dextrose-veal infusion-toe yeast, live bacteria) and in many 

 cases, the diet is still inadequate for reproduction without supplementa- 

 tion with other materials of a complex nature. 



It is generally believed that hookworm infection in man is commonest 

 in areas where malnutrition is prevalent, and that the improvement of 

 the general dietary status of an individual may frequently purify the 

 body of the parasite. Moreover, in experiments using vitamin-deficient 

 rats and the round worm Nippostrongylus muris, 15 it was found that 

 thiamine- and riboflavin-deficient rats contained appreciably more para- 

 sites than did normal controls. Mention of this work is made to empha- 

 size the unreliability of data obtained by deducing the nutritional require- 



