io 4 THE PSYCHIC LIFE 



lar to the plane of division. The first organ that mul- 

 tiplies is the flagellum; it does not split into two parts, 

 as several English authors have supposed; according 

 to the observations of Biitschli and of Klebs, a second 

 flagellum is formed complete. The pigmentary spot 

 also does not divide into two parts; the old eye re- 

 mains by a sort of preference with one of the parts, 

 while the other part acquires a new eye, formed com- 

 plete; this is likewise the case with the mouth and the 

 cesophagus. There are only two elements that multi- 

 ply by division: the chromatophores and the nucleus 

 Now, when we note that the chromatophores contain a 

 body, the pyrenoid, which exhibits the closest analogy 

 of chemical composition with the nucleus, we may 

 properly say that the nuclear elements of the cellule 

 are the only ones that do not reproduce by neoforma- 

 tion at the expense of the protoplasm, as is the case 

 with the cilia and the flagella. 



The reason for this mode of multiplication by nu- 

 clear elements will be comprehended, if we consider 

 the matter in the light of experiments made upon the 

 formative properties of the nucleus. We have seen, 

 in fact, that the nucleus can regenerate the protoplasm, 

 but that the protoplasm cannot regenerate the nucleus. 

 We now see that the regeneration of organs lost in 

 consequence of the spontaneous division of cellules, is 

 subjected to the same law as the regeneration follow- 

 ing upon artificial division; the protoplasm cannot re- 

 generate a nuclear element any more in the one case 

 than in the other; in order to effect reproduction, 

 therefore, this element must divide. 



