X. THE CHANGE OF PROTOPLASM STRUCTURE 



313 



forming bundles ; these elementary bodies are arranged in a regular 

 manner associating loosely with each other. The bodies must be ar- 

 ranged in the protoplasm in an equal direction as otherwise the polarity 

 of the cell or organism may not be raised. If the end-to-end association 

 of the elementary bodies is tighter than the side-to-side association, 

 the protoplasm may appear as if it were composed of protein threads 

 in a parallel alignment, as shown in Fig. 30, but such threads may 

 be invisible under the ordinary microscope. 



A 



B 



D 



E 



Fig. 30 

 Diagram of mitosis 



When the cell, after its full maturation, is brought under the 

 influence of a certain stimulus, the protoplasm particle termed centriole 

 may be activated by the liberation of some active groups, resulting 

 in its vigorous growth until it becomes so large that it fails to exist 

 any more as a single particle which therefore is to be divided. Through 

 the division the structure of the proteins in the particle is disturbed 

 severely, and a kind of denaturation follows with the temporary liber- 

 ation of strong active groups which can attract the elementary bodies 

 present nearby. The elementary bodies thus pulled and combined by 

 the centrioles drag in their turn other elementary bodies successively, 

 and moreover the denaturating process of the centriole is transferred 

 to them, acting as a stimulus to contract the protein threads ; as a 

 result they are coagulated and thus the coagulation is spread centrifu- 

 gally from the centrioles, so that radiating system of fibers, the so-called 

 asters, become visible at least in some animal cells as shown in B in 

 Fig. 30. This denaturating process is transmitted also to the nucleus 



