THE CHROMOSOMES 157 
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 
Fra. 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); f, g, h, twisting of leptotene threads around each other (amphitene 
stage); 7, amphitene stage (entire cell); 7, pachytene stage (bouquet 
pachytene); &, longitudinal splitting of threads (strepsinema stage); l, 
shortening and thickening of the chromosomes. (After Janssens.) 
