SPERMATOGENESIS OF LEPISMA DOMESTICA 387 



brane and retaining the dark stain of the haematoxylin (fig. 15). 

 In addition to the idiochromosomes, a similarly staining, small, 

 spherical granule appears (fig. 13). The chromatin clumps now 

 become granular and form an eccentric 'circle against the nuclear 

 membrane, leaving an open center very much like the condition 

 following the last division. The homogeneous granular border 

 is at first deeply stained, but later loses its affinity for the haema- 

 toxylin and appears pale in color (figs. 11 and 16). 



The idiochromosomes also seem to break up into unequal 

 spherical bodies, three to eight hi number, six being the more 

 common number (fig. 16) . In the clear central region the remains 

 of the preceding spindle are quite apparent. Following this 

 stage we have the reappearance of the idiochromosomes (fig. 17), 

 and after that the entire nucleus appears granular, the central 

 clear area disappearing and the two idiochromosomes stand out 

 clearly (fig. 21). 



It has not been possible to see anything like an unraveling 

 stage as described by Wilson ('12) for stage c; the granular con- 

 dition being directly followed by delicate threads (Wilson, 

 stage d, fig. 22) which seem to push out and distort or break the 

 nuclear wall. This is soon followed by the synizesis or con- 

 traction stage. Here the threads are drawn closely together 

 and are located more to one side of the nucleus, the plasmosome 

 and idiochromosome thread often remain outside of the con- 

 tracted mass, as shown in figure 23. 



Popoff ('08), Gates ('08), and Whiting ('17) look upon this 

 as due to a rapid absorption of water by the nucleus; in other 

 words, an osmotic effect; however, it has often been considered 

 an artifact. Although at this stage of the growth period the 

 spireme threads stain very intensely, making it difficult to trace 

 the individual threads, it would look as though the filaments 

 became arranged in the form of loops polarized with their free 

 ends near the plasmosome and idiochromosome threads. Later 

 on when the threads have thickened, this bouquet stage is much 

 more clearly seen (fig. 25) . 



It has not been possible to see a side-by-side union of the 

 spireme threads, the synapsis of Moore ('95), but the number 



