680 



stances can not entirely fill tbe place of tlie albuminoids, but like ftit 

 and carbohydrates, act as albuuiiuoid couservers, so that an animal 

 may be kept on a food deficient m albumin when gelatiutjus substances 

 are added to it. In an experiment by Weiske, Sclirodt, and v. Dan- 

 gel* on two sheep, the addition of 53 grams of gelatinous substances to 

 a ration consisting of 500 grams hay, 200 grams starch, and 50 grams 

 sugar, increased the amount of nitrogen stored in the body in No. 1 

 from 0.279 gram daily to 1.98 grams, and iu No. 2 from 0.27 to 0.68 

 gram ; while the addition of an equivalent amount of peas in place 

 of the gelatinous substances increased the nitrogen stored in the body 

 with No. 1 to 1.6G8, and with No. 2 to 2.427 grams of nitrogen per day. 



The results for period 7 of the present experiment showed how 

 extensive the action of gelatin in economizing the albuminoids may be, 

 for with its aid the ration of barley straw, containing only 3.25 grams 

 of nitrogen, was sufficient to maiutain an animal weighing over 100 

 pounds, and even enable it to lay on a small amount of nitrogen (1.55 

 grams per day). Since gelatin is not assimilable this 1.55 grams of 

 nitrogen must have come entirely from the straw ; and since this amount 

 is 48 per cent of the total nitrogen in the daily ration of straw (3.25 

 grams) the indications are that the gelatiu prevented the destruction 

 of the digestible albuminoids of the straw quite completely, causing 

 them instead to be stored in the body. 



The object of the last period's feeding (straw and starch) was to fur- 

 nish a basis for comparing the effects of the albuminoid materials. By 

 feediug a nitrogen-free substance (starch) iu place of tbe materials con- 

 taining protein, a factor for the effect of the straw was obtained, which, 

 deducted from the results of each previous period, indicated more 

 closely the effect due to the supplementary food. The animal refused 

 the food after 2 days and the feeding was continued with another sheep. 

 As the nitrogen voided iu the fa3ces was exactly the same, and that 

 in the urine nearly the same as iu the case of the first sheei), the results 

 were considered as reliable for comparisons. The faeces in this period, 

 contrary to those of all the other periods, were strongly acid, and gave 

 a strong reaction for starch. This agrees with the results of Haubuer 

 and others, which have shown that while large quantities of starch 

 were thoroughly digested when fed in a ration with protein substances, 

 they were not completely digested when the protein was diminished 

 beyond a certain limit. 



The results of this experiment do not support the view that either the 

 nitrogen content (Liebig's theory) or the carbon content (Eitthausen's 

 theory) of albuminoid materials can be considered as indicative of their 

 nutritive value, nor do they indicate any apparent relation between 

 the chemical composition of these bodies and their value for food. 

 Taking the observed results in tliis trial as the measure of the values 

 for increasing the store of nitrogen in the body, couglutin, which differs 



"Zoitsch. f. Biologic, 15, p. 261. 



