344 Vitamines and Deficiency Diseases [June-September 



McCollum and Davis (135), 0.02-0.034 percent. Salts were used 

 in the same kinds and proportions as those for the experiments by 

 Osborne and Mendel, but no protein-free milk was added. 



We did not succeed in keeping cur rats longer than two months 

 on this diet. We were unable to see any good effects of the 

 addition of the butter. Slightly better results were obtained, how- 

 ever, with crude butter. Male rats increased in weight, after 42 

 days, 54 percent; females, 41 percent. At that time, in the purified 

 butter series, several rats had already died. After 24 days the males 

 in this group increased their weight by 45 percent, the females by 

 31 percent; whereas, at the same time (24 days) in the crude butter 

 experiments, the weights of the males increased by 66 percent, of 

 the females by 48 percent. 



Both butter preparations were fed in an artificial diet to pigeons, 

 the latter developing beriberi in the usual time in both series. In 

 neither butter samples could any appreciable amount of beriberi- 

 vitamine be detected by this method. 



I would not call our experiments entirely conclusive, especially 

 as further studies are in progress, but I received the Impression that 

 the remarkable results obtained by Osborne and Mendel are due, to 

 a great extent, to the use of protein-free milk. It seems to me that 

 in the experiments of Osborne and Mendel the excellent results are 

 due to the addition of vitamine with casein, lactose, protein-free 

 milk and butter. One of the last papers of McCollum and Davis 

 (135) gives a less enthusiastic account of the influence of butter on 

 growth. They believe that even the butter diet lacks something es- 

 sential which is present in natural food for rats. 



The study on fats was extended to cod-liver oil (Iscovesco, 107) 

 by Osborne and Mendel (136), which was found to have the same 

 action as butter, whereas almond oil and tri-glycerides of the fatty 

 acids had no effect. McCollum and Davis (135) found lard, olive 

 oil, tallow and cotton-seed oil inactive, but the ether extract of dried, 

 ripe cod testicles and pig kidney were very active. 



Recently Osborne and Mendel (137) have fractioned beef- and 

 butter-fat more extensively. Abdominal fat of cattle and butter 

 were dissolved in alcohol at 40° C. and allowed to crystallize. The 

 crystallin fraction was ineffective. The oily part, which was 



