536 



CELL MECHANICS 



ing part of the chromosome at its " spindle attachment " has long 

 been recognised. Owing to its variable appearance and interpreta- 

 tion, different names have been given to it by different workers 

 (Table 75) . It has been identified at metaphase of mitosis in plants, 

 at pachytene in animals and later in plants, at first metaphase of 

 meiosis in plants (Minouchi cit., Kuwada, 1928 ; D., loc. cit., 

 and 1936 d). Special conditions of fixation and staining are neces- 

 sary to show it, and probably it is beyond the limit of visibility in 

 small chromosomes. In the largest chromosomes it appears to be 

 0*2 yu, in diameter with a chrom-acetic fixation, and larger with 

 acetocarmine. With the first method its differential staining is 



Table 75 

 Names Applied to the Centromere and the Centric Constriction 



