124 



THE CHROMOSOMES 



where some of the ends can be seen to be arranged in 

 pairs. As they unite in pairs these thin threads 

 often have the appearance of twisting tightly around 



FIG. 43. Spermatogenesis of Batracoseps attenuatus. a, late telophase 

 of spermatogonial division ; b, resting stage after the last spermatogonial 

 division; c, appearance of the spireme; d and e, later stage of last (bouquet 

 grele) ; /, g, h, twisting of leptotene threads around each other (amphitene 

 stage); i, amphitene stage (entire cell); j, pachytene stage (bouquet 

 pachytene); fc, longitudinal splitting of threads (strepsinema stage); I, 

 shortening and thickening of the chromosomes. (After Janssens.) 



