ALL VITAL WORK. 155 



that every manifestation of vital action is due to the 

 -consumption of " irritable matter " a nitrogenous 

 substance in a peculiar state of combination and also 

 with the identical hypothesis of Beale in respect to 

 *' germinal matter," both now corresponding to proto- 

 plasm. It is quite possible, however, that the actual 

 evolution of force may take place in an intermediate 

 chemical compound formed by the protoplasm, and 

 that may be even of such a nature, according to the 

 hypothesis of Traube and L. Hermann, as to allow the 

 compensatory process to take place within the muscle, 

 and that this explains the non-increase of urea. However 

 this may be, the difficulty here is no greater than for 

 the whole doctrine of Beale, viz., that all nutrition and 

 .secretion are produced by the death or decomposition 

 of protoplasm i.e., a nitrogenous substance while 

 many of the products are simple binary or ternary 

 compounds. We are obliged to assume that in the 

 perfect and complex machinery of the living organism, 

 the molecules are arranged and re-arranged through a 

 long series of still unknown compounds, so that the 

 more simple and effete compounds only are finally 

 excreted and thus the nitrogen is retained. The facts 

 .are also in accordance with this, for with a diet of 

 purely nitrogenous matters, in many animals all func- 

 tions can be performed, and heat and work kept up, 

 .and the formation of fat and other secretions goes on. 

 In such a diet, then, is the maximum of urea excreted ; 

 but, as we substitute non-nitrogenous articles, these 

 are consumed and their products excreted, and the 

 quantity of urea comes down to a certain minimum, 

 below which it cannot fall, however rigidly non-nitro- 



