On Blood- Platelets. 



449 



growth of fish has been found much more uniform throughout the year ; the 

 changes in the production of plants are there not so marked as in the high 

 Northern latitudes. 



Dr. Palmgren and I intend, if circumstances permit, to continue the 

 investigations towards the solution of these problems at the Biological 

 Laboratory of the University of Christiania. 



On Blood-Platelets : their Behaviour in " Vitamin A " Deficiency 

 and after " Radiation" and, their Relation to Bacterial 

 Infections. 



By W. Cramer, A. H. Drew, and J. C. Mottram. 



(Communicated by Prof. W. Bulloch, F.R.S. Received March 28, 1922.) 



(From the Laboratories of the Imperial Cancer Research Fund and from the 



Radium Institute.) 



Introductory. General Effects of Fat-soluble Vitamin Deficiency. 



When the fat-soluble vitamin A is withheld from the diet of a rat, the 

 general condition of the animal differs from that resulting from a deficiency 

 of the water-soluble B vitamin. In the latter case the animal ceases to 

 increase in weight almost at once, and then begins to decline. There is a 

 progressive fall in the temperature. The animals always die within a 

 comparatively short time — two months — and are then found to be in a state 

 of profound emaciation, as if. they had received no food at all. There is no 

 obvious sign of disease or of an infection. For the sake of convenience, we 

 will designate briefly this condition by the term " marasmus." 



The withholding of the fat- soluble vitamin A alone affects s different 

 individual rats in a- manner as varied and indefinite as the conditions 

 obtained by a deficiency in the water-soluble B are constant and definite. 

 When a young rat is kept on a diet from which the fat-soluble vitamin A is 

 absent, the increase in weight may cease almost at once, or it may continue 

 to increase in weight for many weeks, and almost as rapidly as on a diet 

 containing vitamin A, although eventually its growth will come to a 

 standstill before the full normal size of an adult rat has been reached. 

 We shall, for the sake of convenience, describe these two extremes as the 

 " acute " and the " chronic " effect on growth respectively. Eventually the 



vol. xciii. — b. 2 K 



