MORPHOLOGICAL UNITY OF LIVING BEINGS. 165 



thread, and the filaments themselves (mitome) show 

 very thick chromatic granulations, or microsomes, 

 connected by the linin. 



At the moment of reproduction of the cell these 

 granulations blend into a stainable sheath which 

 surrounds the filaments, and the latter dispose them- 

 selves so as to form a single thread. This chromatic 

 filament, which has now become a single thread, is 

 shortened as it thickens {spireme) ; it is then cut into 

 segments, twelve or twenty-four in the case of animals 

 and a larger number in the case of plants. These 

 are chro7Hoso7nes, or nuclear segments, or chromatic 

 loops. Their part is a very important one. They 

 are constant in number and permanent during the 

 whole of the life of the cell. Let us add that the 

 nucleus still contains accessory elements (nucleoli). 



The Role of the Nucleus. — Experiment has shown 

 that the nucleus presides over the nutrition, the 

 growth, and the conservation of the cell. If, following 

 the example of Balbiani, Gruber, Nussbaum, and 

 W. Roux of Leipzig, we cut into two a cell without 

 injuring the nucleus, the fragment which is denuded 

 of the nucleus continues to perform its functions for 

 some time in the ordinary manner, and in some 

 measure in. virtue of its former impulse. It then 

 declines and dies. On the contrary, the fragment 

 provided with the nucleus repairs its wound, is 

 reconstituted and continues to live. Thus the nucleus' 

 takes a very remarkable part in the reproduction of 

 the cell, but it is still a matter of uncertainty whether 

 its role is here subordinated to that of the cellular 

 body, or if it is pre-eminent. However that may be, 

 it follows from this experiment that the nucleus 

 presents all the characteristics of a vigorous vitality, 



