116 Life and Death, Heredity and Evolution 



or the building up of organic material, with the storing up 

 of energy, while in the male the prevailing process is catabo- 

 lism, or the breaking down process by which energy is set 

 free, this energy showing itself in greater movement. Or 

 the male has been called "kinetic," the female "trophic"; 

 or the male progressive, the female conservative ; or it is said 

 that in the male the animal functions prevail, in the female 

 the vegetative functions. 



In recent times emphasis has been laid on a parallel 

 diversity observable between certain parts of the cell or 

 parts of nuclei. When the cell divides, certain parts seem 

 to actively initiate and carry on the movements that bring 

 about division, while other parts are passively moved by 

 these active portions. In many organisms a structure called 

 the aster, which in some cases itself appears to be derived 

 from a small body called the centrosome, sets up at the time 

 of division a great activity in the protoplasm, forming the 

 spindle, and taking the lead in the activities of cell division 

 (see Figure 32). Another portion of the cell, comprising 

 the part commonly called the nucleus, and particularly the 

 chromosomes, is apparently passively moved by these active 

 portions. In some Protozoa there are two nuclei, one of 

 which, the so-called kinetonucleus or blepharoplast ( see Fig- 

 ure 27), is connected with the organs of motion, and is sup- 

 posed by some to correspond to the centrosome. The other, 

 the so-called trophonucleus, appears more passive, and is 

 held to have functions connected primarily with metabolism. 

 The materials of which these two parts are composed are 

 called respectively kinetoplasm and trophoplasm, and it is 

 held by the upholders of this doctrine that these two kinds 

 of material are present, either mingled or separate, in every 

 cell that can divide. 1 



1 A r6sum6 of the facts on which this notion is based is found in the 

 paper of Dobell (1909). 



