456 Messrs. W. Cramer, A. H. Drew, and J. C. Mottram. 



experiment the difference, although still present, was not so striking. In the 

 present experiment the blood was examined at different times after the with- 

 drawal of vitamin A in such a way that the number of platelets in a rat 

 of one group could be compared with that of a rat of the other group on 

 the same day. The results, which are arranged in this way in the Table 

 to fig. 1, show clearly that both groups develop a progressive throrabopenia, 

 but that this thrombopenia advances much more rapidly in the severely 

 affected litter X than in litter Y. 



Fig. 2 refers to four rats which react in the usual way to the withdrawal of 

 the fat soluble vitamin from the diet, and requires no further explanation. 



'■™*"7 "" k *TJ 1 ' ' 8 ' ' 12 ' ' 16 WEEKS 



X- EYE LESION 



Fig. 2. — Weight curves and platelet count of four rats kept on a vitamin A-free diet. 



Table to Fig. 2. 



No. of 

 rat. 



Weeks of • 

 A deficiency. I 



Red cells. 



Platelets. 



Condition of rat. 



269 



8 

 16 



8,720,000 

 8,240,000 



249,000 

 280,000 



No eye symptoms. 



273 



12 



6,720,000 



154,000 



Intense xerophthalmia. 

 Bacteria in blood. 



274 



7 

 15 



10,760,000 

 10,320,000 



680,000 

 380,000 



Xerophthalmia. 



275 



6 

 16 



8,000,000 

 7,800,000 



313,000 

 160,000 



Eye symptoms developed 

 two weeks after this 

 count. 



We have stated above that, when A is withheld, the amount of vitamin B 

 supplied determines to a certain extent the onset of the typical symptoms. 



