AMITOSIS 



27 



Cyclops were placed in weak solutions of ether in water, with the result 

 that, though arrtitosis was not produced, the normal course of mitosis 

 was superficially much altered. The anaphase and telophase especially 

 acquired a superficial resemblance to the later stages of amitosis, owing 

 to a tendency of the chromosomes to start their telophase metamorphosis 

 before they had completely separated in metaphase. The anaphase 

 thus consisted of two confused masses of chromosomes, which began to 

 draw apart while still connected with one another, foiming an hour- 

 glass figure not unlike that formed by a nucleus dividing amitotically 

 into two. The modification of the normal course of mitosis thus induced 

 does not result in death of the nucleus, for eggs removed from the ether 

 solution into pure water resumed normal development. 



Very similar results were obtained by Nemec (1904) by the action of 

 chloral hydrate on the root tips of several of the higher plants. 



It is probable, therefore, that the apparent amitosis observed by 

 Nathansohn was really a modified mitosis, i.e. a division preceded by 

 chromosome formation. 



Proliferation by amitosis has often been described in pathological 

 growths, but here again there is no proof that normal mitosis may follow. 



Summing up as regards the Metazoa and Metaphyta, it is extremely 

 improbable that normal mitosis ever takes place in nuclei produced by 

 true amitosis — that is to say, by direct mass division of the nucleus 

 without any sort of formation of chromosomes and their division into 

 daughter chromosomes for partition to the daughter nuclei. 



A summary of the Uterature on the subject of amitosis in the Metazoa 

 and Metaphyta is given by Nakahara (1918). 



The question of amitosis in the Protista must be reserved to 

 Chapter VII. 



