THE GENERAL CONSTITUTION OF LIVING BEINGS. 95 



cult questions that we have enumerated above. In his 

 view, the ordering and adjustment of the parts flow from 

 the very fact of the gradual formation of those parts, and 

 of the properties inherent in them. He shows how an ex- 

 planation is to be found in the simultaneous operation of 

 properties consubstantial with the elements, in the logical 

 connection of generative, evolutionary, and nutritive acts, 

 of all that had been heretofore attributed to the presence 

 of a so-called vital principle. 



The hypothesis of a vital principle which coordinates 

 and rules the phenomena of life seems to contradict the 

 fact, in this sense, that it is in the first place impossible 

 to fix the exact moment at which this principle intervenes. 

 We have the ovule that is, a mere simple anatomical ele- 

 ment, containing the vitellus. That ovule is already en- 

 dowed with life while it is still dependent on the ovary. 

 By an uninterrupted and inevitable chain of progress other 

 anatomical elements unfold in it, in an ordained sequence, 

 from the moment that it ceases to be part of the ovary 

 until the moment that the embryo is formed. This latter 

 comes forth in the embryonic dot in the same way as the 

 vitelline nucleus does in the vitellus. Each element, by 

 the very fact of its existence and of the performance of the 

 part peculiar to it, here becomes the condition of exist- 

 ence of other elements necessarily appearing in the me- 

 dium which it has engendered, and conducting themselves 

 as it has done. Therefore, at what instant and in what 

 way could a vital principle intervene in this series of en- 

 genderings ? 



It being known that the whole function of the vitellus 

 is to present in succession those conditions required for the 

 genesis of the different elements of the embryo, and that 

 these are parts of one whole process, it is plain that, if one 

 of the acts of development be hindered or modified, it will 

 no longer go on in a regular manner. Experience entirely 



