128 THE VITAMINES 



hence the difficulty of studying problems of nutrition. We know 

 comparatively little of their vitamine requirements, particularly as 

 to vitamines A and B, since in the study of experimental scurvy, 

 dietary mixtures are used containing both of these vitamines. Hume 

 (358a) has recently found that guinea pigs require vitamine A and 

 hence these animals can be used for the detection of vitamine A in 

 green foods but not in fats. Tozer (358b) , in a pathological investi- 

 gation of these animals could not find any difference between experi- 

 mental scurvy and the changes produced by lack of vitamine A. 



FIG. 30. LONGITUDINAL SECTION OF A RIB OF A SCORBUTIC GUINEA PIG^ 



WITH FISSURES, HEMORRHAGES IN THE PERIOSTEUM AND PALE 



MARROW (HOLST-FROLICH) 



We owe the discovery of experimental scurvy to Hoist and Frolich 

 (359) in 1907, although in 1895 a similar condition was observed in 

 the same species by Theobald Smith (360). Hoist and Frolich 

 investigated scurvy in various animals and chose the guinea pig as 

 most suitable for this purpose. It appeared to be unnecessary to 

 choose a special diet, for these investigators noted that scurvy could 

 be produced in guinea pigs with any diet that would do the same 

 in man; this was also the case with any diet that was autoclavedat 

 a high temperature. They recognized, with great perspicacity, that 

 the symptoms were closely analogous to those in man. Guinea pigs 



