80 NATURE AND LIFE. 



proved. It is very plainly seen that cells which have be- 

 come individualized by splitting up, are the seat of a di- 

 vision which gives rise to other cells ; but that only occurs 

 when the mother-cells have gained or exceeded their com- 

 plete development and their regular dimensions. Now 

 this fact, which has been taken as the starting-point of the 

 cellular theory, is a mere phenomenon of evolution, and 

 not a fact of production. The inventors of that theory, 

 for want of observing closely and continuously enough, 

 have quite as widely misunderstood what takes place when 

 we see certain anatomical elements succeed to others of a 

 different kind, as in the case of the liquefaction of one set 

 of elements, and then the formation of a blastema in which 

 the second set is produced. This is a real genesis by sub- 

 stitution, as Robin calls it, and not a direct emission, a 

 proliferation, as is taught in the schools across the Rhine. 

 In this case there are several phases which have escaped 

 the observation of the too systematic doctors of Berlin 

 and Wurzburg, but which French savants have settled in 

 a way not to be gainsaid, not being blinded, like the for- 

 mer, by a preconceived idea. What these same Germans 

 call endogenous generation, that is, generation within a 

 cell, is quite as much an exceptional mode of production of 

 anatomical elements, but one that in no way contradicts 

 those we have enumerated, and in no way avails to prop up 

 Schwann's theory. The cellular theory is a doctrine as de- 

 lusive as it is convenient and attractive. It is one of the 

 numerous mistakes introduced into German science by 

 that philosophy of Nature so highly relished by the con- 

 temporaries of Schelling and Oken, and of which the traces 

 are to be found in the works of man}- eminent savants of 

 Germany even at this day. Flattering as it is to that in- 

 clination by which we are led to the desire to confound 

 things the most disparate in one chimerical unity, it is not 

 surprising that such a philosophy should so long have im- 



