VITAMIN B (5i) 105 



the "cart-wheel turnings" of pigeons described by Kon and Drummond 

 (1927). 



An amount of the vitamin which allows approximately net mainte- 

 nance of the weight of the experimental animal over an eight week 

 period, is frequently insufficient for protection from the deficiency, and, 

 as pointed out by Sandels (1930) may permit the development of a 

 subacute or chronic type of polyneuritis. Animals in this condition 

 usually maintain life for several weeks, and the majority of these show 

 definite symptoms of polyneuritis continuously after the deficiency has 

 once become manifest. Vedder and Clark (1912), Weill and Mouri- 

 quand (1919), and Randoin and Lecoq (1927i) reported a similar 

 condition in fowls receiving an amount of vitamin insufficient for full 

 protection. Hofmeister (1922) also described this subacute type of 

 polyneuritis, and associated the condition with shortage rather than 

 complete absence of the antineuritic vitamin. For a fuller and recent 

 discussion of this point, see the paper of Sandels (1930). 



Proposed Injection Method. — Smith (1930) suggests that the rela- 

 tive antineuritic potency of preparations be determined by finding the 

 minimum dose which when injected intravenously will cure polyneuritic 

 rats for 3 days. He finds that the period of recovery is roughly pro- 

 portional to the size of the dose administered, and that when paralysis 

 intervenes again it can be alleviated a second or third time, thus making 

 it possible to use the same animal for several tests vdth but little change 

 in its response to the influence of the vitamin. In his investigation 

 the autoclaved brewers' yeast used as a source of vitamin G apparently 

 contains enough vitamin B to prolong the life of the rat sufficiently to 

 permit quite regular development of polyneuritis. 



Stability of Vitamin B 



Sherman and Spohn (1923) found no measurable diminution of 

 vitamin B in milk powder when heated dry with free access to air 

 at 100° C, when this heating was continued even for 48 hours. When 

 the milk was heated in the fluid state for 6 hours at 100° C. about one- 

 fourth of the vitamin B content was destroyed. Although these experi- 

 ments were conducted before vitamin G was recognized, it is quite cer- 

 tain that the results were not vitiated by lack of vitamin G both because 

 it has been amply demonstrated that cow's milk is relatively richer in 

 vitamin G than vitamin B (at least, in terms of the nutritional needs 

 of the albino rat) and because vitamin B is the more thermolabile of 

 the two. 



Daniels, Giddings and Jordan (1929) report that the degree of 



