CHAPTER XXXIV 

 KARYOKINESIS, OR INDIRECT CELLULAR DIVISION 



THE progress of histological investigation has brought about 

 the discovery, in cell division, of morphological manifesta- 

 tions which are a further proof in favour of intraprotoplasmic 

 bipolarity. Professor Angel Gallardo, of Buenos Ayres, 

 was the first to propose a bipolar theory of the karyokinetic 

 phenomenon. 



In karyokinesis there are nucleary manifestations and 

 cytoplasmic manifestations. 



The former have chiefly attracted the attention of students. 

 They principally consist in a modification of the distribu- 

 tion of intranuclear chromatic substances, that is, of the parts 

 of the nuclear protoplasm which are most avid of basic aniline 

 colours. These chromatic substances, which are at first 

 distributed in the form of an irregular network (Fig. 20, 

 A), take the form of a long winding filament, or spireme 

 (Fig. 20, B). Next, this winding filament is cut into 

 a fixed number of pieces, or chromosomes (n in the prothallus 

 state, 2n in the fern state), each of which divides longitundin- 

 ally into two parallel bead-strings. To these chromosomes 

 has been attributed particular value in phenomena of the 

 hereditary transmission of characters ; but this is an 

 hypothesis which nothing verifies. 



In any case, this new distribution of the chromatic sub- 

 stance shows profound transformation in the equilibrium of 



