50 PHYSIOLOGY AT THE FARM. 



that during that period caseine is rapidly converted either 

 directly or indirectly at least into albumen and fibrine. The 

 ultimate composition of the three substances caseine, fibrine, 

 albumen differs but in a very slight degree. Every one of 

 the three consists of carbon, hydrogen, nitrogen, and oxygen, 

 very nearly in the same absolute proportions, notwithstand- 

 ing the very decided differences in their sensible properties. 

 It seems established, however, that albumen and fibrine con- 

 tain besides less than two per cent of sulphur and phosphorus, 

 while caseine contains no phosphorus, but only sulphur. 

 Though chemists are not yet satisfied that caseine can be con- 

 verted into albumen or fibrine in the laboratory, there is 

 nevertheless no difficulty in conceiving that this transmutation 

 should readily take place in the living system, under the vari- 

 ous circumstances operative during the progress of digestion, 

 especially in its ulterior stages. It has often happened that 

 chemists, after long trying in vain to produce certain com- 

 binations of elements, at last succeed by employing a more com- 

 plete apparatus and nicer adjustments ; but what can exceed 

 the perfection of the means provided for the accomplishment 

 of ends in organic nature, even though the final effect be the 

 result of nothing more than the ordinary affinities prevalent 

 among simple substances ! 



The general plan on which transmutation of one organic 

 principle into another takes place in living nature, is that a 

 portion of the substance to be augmented is mingled with 

 the substance which is to undergo transformation in contact 

 with a living surface. Thus in vegetation the carbonic acid, 

 watery vapour, and ammonia of the atmosphere absorbed into 

 the cells of the leaves of plants are metamorphosed, under the 

 influence of the sun's rays, into the vegetable proximate prin- 

 ciples already existing in those cells viz., albumen, lignine, 

 starch, sugar. Changes of the same character are even ob- 



