182 MONTGOMERY A STUDY OF THE CHROMOSOMES 



shaped, and so would be bivalent. Sometimes one of them appears rounded or oval 

 instead of dumbbell-shaped ; this may be a bivalent one seen obliquely, or it might 

 possibly be a univalent one ; the lack of knowledge of the spermatogonic number does 

 not permit us to decide which. 



24. Ichnodemus falicus Say 



Five testes of this species were studied. 



Cliromatin nucleoli were not determined in the rest stage of the sperm atogonia. 

 But they are very probably present there because two small rounded ones can be seen in 

 the late spermatogonic prophases ; whether more than two I could not determine. All 

 the testes examined had been fixed with picro-acetic acid, causing such a swelling and 

 consequent juxtaposition of the chromosomes that in only one case were they sufficiently 

 separated to be counted (PI. IV, Fig. 145), and here fourteen chromatin elements were 

 present. Since in the first maturation spindle there are always seven bivalent chromo- 

 somes, I should think that the fourteen elements of Fig. 145 are univalent chromosomes, 

 and that in this monaster the chromatin nucleoli are hidden. 



In the monaster stage of the first maturation division are seen on pole views (Figs. 

 147, 148) always seven larger elements, which on lateral view are found to be all dumb- 

 bell-shaped, and so are probably bivalent. All these seven elements are presumably 

 chromosomes corresponding to the fourteen found in the spermatogonia (Fig. 145). 

 Besides these are to be seen at this stage, and also in the preceding prophases (Fig. 146), 

 two or three smaller elements, which are presumably chromatin nucleoli. Generally 

 three of these are found (JV. 2, Figs. 146, 147), and generally the case is as in Fig. 146, 

 two larger and one smaller. The two larger being generally of approximately equal 

 volume (Figs. 146, 148), it is quite probable that taken together they may represent 

 one bivalent chromatin nucleolus with separated components. The smaller one some- 

 times appears transversely constricted, as in Fig. 146, so this one may also be bivalent ; 

 if this is the case, then there should be four univalent ones in the spermatogonia. But 

 the number of them could not be determined in the spermatogonia, and in the growth 

 period of the spermatocytes the stain was not favorable for showing their relations. 



25. Peliopelta abbreviate Uhl. 



Five testes of this species were studied. 



In a pole view of the spermatogonic monaster (PI. IV, Fig. 149, the only clear case 

 observed) are found sixteen chromatin segments, ten of which are larger and more 

 elongate than the others, while six are rounded and smaller. The two smallest (N. #) 

 are probably chromatin nucleoli, by analogy with other species of the Lygceidce. 



