NUTRITION. 397 



pears furnish some water-soluble vitamine; the quantity of these fruits 

 necessary to supply this dietary essential is relatively very large, so 

 that from a comparative standpoint they can not be regarded as rich 

 in this food factor. Prunes apparently are somewhat richer m the 

 water-soluble vitamine. 



From preliminary experiments it seems doubtful whether the juices 

 of the lemon or grapefruit contain more than traces, if any, of the fat- 

 soluble vitamine. Our observations upon orange juice, however, are 

 indicative of some potency in this vitamine. 



The experiments with fruits place the dietary value of these foods, 

 hitherto recommended because of their salt content, their laxative prop- 

 erties, or their antiscorbutic potency, in a new light as sources of water- 

 soluble vitamine. 



Our earUer investigations on the water-soluble vitamine content of 

 fresh milk were carried out during the winter season, when the cows in 

 this region are deprived of green pasture and are stall-fed. It seemed 

 not impossible that the relatively large quantity of milk necessitated 

 as a source of water-soluble vitamine in those experiments might be 

 associated with quality of milk inferior from the vitamine standpoint, 

 owing to the winter diet of the cows. Consequently, we have under- 

 taken a further series of experiments in which varying quantities of 

 unpasteurized milk, ob tamed fresh from cows known to be feeding in 

 open pasture, furnished young rats with the sole source of water- 

 soluble vitamine. The outcome has been the same as that of the 

 earlier experiments. With additions of 2 c. c. of summer milk no per- 

 manent gains were secured. Additions of 5 c. c. invariably produced 

 better, though by no means adequate, growth; nor was the latter usually 

 obtained with daily additions of 10 c. c. of summer milk. Whenever 

 the vitamine supplement in the form of milk was still further in- 

 creased, improvement in the rate of growth occurred. The inferiority 

 of even 15 c. c. of the fresh, unpasteurized summer milk as a source of 

 water-soluble vitamine, in contrast with 0.2 gm. of dried brewery 

 yeast, was indicated by the more rapid gains made by all the animals 

 thus tested when the yeast addendum replaced the milk. Even 15 

 c. c. of the summer milk fed from the start barely sufficed as a source 

 of water-soluble vitamine to promote growth at a normal rate. 



Incidentally an opportunity has been afforded during the past year 

 to make a few feedmg experiments with human milk with a view to 

 testing its potency as a source of water-soluble vitamine. From the 

 very limited data thus far secured there is no evidence of a greater 

 content of this food factor in this important nutrient than in cow's 

 milk. More extensive investigations of the vitamine properties of 

 human milk are desirable. 



The study of the relative content of water-soluble vitamine in the 

 various vegetable products has been continued. In these experiments 



