M. Dumas on the Constitution of Milk and Blood. 125 



domain, we are sure to see the demonstrations of the appropri- 

 ateness of this reserve multiplied. 



Among the fine investigations executed in France by those 

 who have continued the labours which occupied the life of the 

 illustrious Theodore de Saussure, the important thesis of M. 

 Raulin upon the vegetation of Aspergillus niger will always 

 be placed in the foremost rank. All the conditions of the 

 life of this Mucedinean have been so well determined by that 

 author that it may be cultivated with precision in a soil 

 formed of definite chemical species, as if we had to do with 

 the formation of a compound ; and the soil once sown, we may 

 follow the transformation or the employment of each of the 

 elements necessary to its life, just as if we had to do with the 

 development of an ordinary chemical equation. 



Now, who could have foreseen that the Aspergillus niger^ 

 which has just made its appearance, for example, upon a slice 

 of lemon exposed to the air, required for the fulness of its 

 existence traces of oxide of zinc ? How, after this, can we 

 doubt, in the case of plants of a higher order and especially of 

 animals, that, besides their coarsely appreciable aliments, they 

 require also traces of many other aliments, more delicately 

 used but not less necessary ? 



Milk has often been compared to eggs, both from a che- 

 mical and a physiological point of view. Their mission is 

 equally to furnish the young animal with the nourishment of 

 its earliest age ; and they have as a common character that 

 they present in union a fatty matter, an albuminoid substance, 

 a saccharine or amylaceous matter, and salts. 



But the ^^^ possesses a vitality, an organization, of which 

 chemistry furnishes no evidence, and which the most minute 

 anatomy would be powerless to reveal. If fecundation had 

 not rendered manifest, by the rapid phenomena of segmenta- 

 tion which take place in it, that the mass of the yelk of an 

 ^gg is endowed with life, and that it obeys the impulsion of 

 the living germ which takes possession of it, we should still 

 be ignorant that the yelk of the q,^^ is not a mere emulsion of 

 inert fatty matter. 



Is not milk in the same case? One is led to think so 

 when we see that the yelk of the ^g^g and milk have the same 

 destination and the same configuration, and that, if the yelk 

 obeys the action of the germ which is nom-ished by it, milk, 

 for its part, proves to be singularly ready to receive and 

 nourish germs of more than one kind, which, on reaching it, 

 become developed and live at its expense. 



The power of synthesis of organic chemistry in particular, 

 and that of chemistry in general, have therefore their limits. 



