8 4 



Scientific Proceedings (104). 



same time; sometimes, also, the infection produced remains 

 unseen by microscopical examination and is only detected by 

 killing the inoculated animal and by sub-inoculating another rat 

 with blood from it. Inoculations are less likely to fail, or result 

 in unobvious infection when considerable quantities of blood 

 are inoculated. 



In order to obtain considerable quantities of material for inocu- 

 lation from rats in which spirochetes could not be found by 

 blood examinations, blood was aspirated from hearts and spleens 

 were excised. Of these two methods the aspiration of heart's 

 blood was the more successful. Under chloroform, it is easy to 

 aspirate from 1 to 2.5 ccm. of blood from the heart of an adult rat 

 without injuring the animal. By so doing, spirochaetes were 

 shown, in one instance, to be present in an apparently immune 

 rat thirty-two days after the parasites were last seen by the daily 

 examination of blood films. Previously, this rat had twice been 

 infected by inoculation and had acquired an immunity shown by 

 two unsuccessful inoculations. Two subsequent, also unsuccessful, 

 inoculations showed that the rat was still immune to the strain 

 employed in this experiment. 



It should be remarked that several similar experiments did not 

 reveal latent infections in immune rats. 



50 (1510) 



The influence of water-soluble vitamine on the nutrition of dogs. 

 By W. G. Karr (by invitation) 



[From the Sheffield Laboratory of Physiological Chemistry, Yale 

 University, New Haven, Ct.] 



Studies on a few species of animals have indicated that the 

 water-soluble vitamine is of importance to nutrition during all 

 stages of life and that prolonged absence of it from the diet will 

 lead to a diseased condition. In the present investigation the role 

 of water-soluble vitamines in the nutrition of the dog has been 

 under consideration. 



The animals were fed a diet devoid of water-soluble vitamine 

 and consisting of lard, sucrose, inorganic salts, and protein in the 



