122 [May 22, 



The weight, temperature, and general condition of the animals 

 were especially noticed, and in some cases the urine was collected and 

 the amount of nitrogen it contained determined. 



From these experiments the following conclusions are drawn : 



Nitrogenous materials are not only calorifacient, but, at least under 

 some circumstances, sufficiently so to maintain alone the requisite 

 temperature. 



It is in the highest degree probable that, under certain circum- 

 stances, nitrogenous materials may prove directly calorifacient without 

 forming tissue. 



Non-nitrogenous substances are, at least under some circumstances, 

 directly calorifacient without entering into the composition of tissue 

 of any kind. 



While non-nitrogenous food only is taken, all the nitrogen which 

 is excreted in the urine, and more, may be accounted for by the dis- 

 integration of the original tissues, without assuming that any fraction 

 is assimilated from any other source. 



While life cannot be maintained without nitrogenous food, even 

 though every other kind be abundantly supplied, death in this case 

 being due to loss of tissue, life and even health and the normal tem- 

 perature can be maintained, at least for a long period, upon a diet 

 almost exclusively nitrogenous, with proper inorganic substances in 

 which there exists only a small fraction of non-nitrogenous matter. 

 Such a minute proportion of fat must be but a poor representative of 

 non-nitrogenous food. 



Moreover in these experiments some of the rats sustained a loss 

 of weight considerably above 50 per cent. 



The difference in this respect between former experiments and 

 mine may be, perhaps, in some measure accounted for by considering 

 the immediate cause of death in the former ones. Chossat satisfac- 

 torily showed that the subjects of his experiments died from cold. 

 In my experiments, the animals being freely supplied with calorifa- 

 cient food, this cause of death was for a while averted, so that time 

 was allowed for a further disintegration of tissue. 



When their temperature is maintained from external sources, or 

 when they are freely supplied with calorifacient food, warm-blooded 

 animals may die rather from waste than loss of temperature, as 

 perhaps is the case with cold-blooded animals when they are starved. 



