LESSON XXXVI. 



CELL-DIVISION. 



1. Sections of salamander. (Flemming's fluid.) 



Place some sections in alcoholic saffranin for 1 to 2 days; 

 pass through alcohols and leave in absolute alcohol until the 

 excess of colouring matter is extracted, clear with cedar-wood oil 

 and mount. 



Stain other sections with hsematoxylin, treating afterwards 

 with acid alcohol. 



Note the following stages of nuclear division : 



The tangle, consisting of one or more filaments. 



The star in which the division of the filaments into 

 chromosomes is complete, and the bent portion of the 

 chromosomes is directed approximately to the centre of 

 the nuclear space. 



The stage of meta-kinesis, in which most or all of 

 the primary chromosomes have divided longitudinally, 

 forming the secondary chromosomes. The secondary 

 chromosomes are arranged in two groups with the bent 

 portions in each group pointing away from the centre 

 of the nuclear space. (Each set is directed towards 

 the region to be occupied subsequently by the daughter 

 nuclei.) 



