METHODS 11 



phenomena properly so called, while they are not found 

 above the dimension of the cell, do extend to smaller manifes- 

 tations of atomic or chemical order. We shall have to seek 

 the lower limit of dimension of biological phenomena ; it 

 may be given us in the dimension of the least radiations of 

 ether which are able to influence vital phenomena. We must 

 be content with this first approximation for the present, 

 keeping hold however of this very important fact before 

 everything else in the study of biological phenomena comes 

 the question of a scale of magnitudes. 



Some of the great biological laws, that of the heredity of 

 acquired characters for example, at first sight seem not to 

 fall under this necessity of being connected with phenomena 

 placed within restricted limits of dimension. But if such 

 laws are really biological, that is, general, we may be sure 

 beforehand that the means by which they manifest them- 

 selves will belong to the order of magnitude of biological 

 phenomena ; and so heredity, a resemblance among beings 

 as large as you please, will be realized by means of the egg, 

 which is a cell. 



Embryology gives no new biological results for the reason 

 that, having only recently become a science and being the 

 child of the cellular theory, it is still distinguished with 

 difficulty from histology. Embryology is the histology of 

 very young beings. 



