168 MONTGOMERY A STUDY OF THE CHROMOSOMES 



COREIDJE. 



13. Anasa tristis De G. 



Twenty-one testes of this species were studied. 



In regard to the chromosomal numbers my observations confirm those of Paulmier. 



In the rest stage of the spermatogonium (PI. II, Figs. 72, 73) there are two chro- 

 matin nucleoli (N. #), which are much smaller than the true nucleoli (N) to which they 

 are generally apposed. They have definite irregularly rounded or oval outlines as 

 examined with Hermann's saffranine-gentian violet stain, and are not " hazy " or " indefi- 

 nite " as Paulmier (1899) described. Both may be attached to the same nucleolus, or they 

 may be joined to separate nucleoli. Sometimes each one may separate into two pieces (as 

 is the case with one in Fig. 72). They are best seen on iron haematoxylin preparations 

 so strongly destaiued that the chromatin reticulum does not appear. 



In the monaster stage of the spermatogonia (Fig. 74) are twenty-two chromatin seg- 

 ments, namely, twenty larger chromosomes and two much smaller chromatin nucleol 1 

 (N. *). 



In the synapsis stage the twenty chromosomes unite to form ten bivalent ones, and 

 the two chromatin nucleoli to form one bivalent one. The latter is clearly bipartite in 

 the synapsis, but later shows an oval outline (Fig. 75) ; it is peripheral in position, often 

 contains a central clearer vacuole as in the Pentatomidce, and is as a rule separated from 

 the true nucleolus (^V). 



In the monaster stage of the first maturation division (pole view, Fig. 76) are found 

 eleven bivalent, dumbbell-shaped chromatin segments, of which the central, smallest one 

 is the chromatin nucleolus (N. 2). I am able to confirm Paulmier's (1899) account of 

 the two maturation divisions. 



14. Anasa armigera Say 



One testis of this species was studied. 



The spermatogeuesis seems to be very similar to that of the preceding species, but 

 as I had no preparation stained with saffranine-gentian violet I was unable to determine 

 the relations of the chromatin nucleoli in the rest stage of the spermatogonia. 



Fig. 77, PI. II, shows a pole view of a monaster stage of the spermatogonia, with 

 twenty chromosomes and two chromatin nucleoli (N. 2}; it is very similar to the corre- 

 sponding stage in Anasa tristis (Fig. 74). 



In the synapsis are formed ten bivalent chromosomes and one bivalent chromatin 

 nucleolus. 



In the monaster of the first maturation division (Fig. 78) are ten bivalent chroino- 



