OF THE GEBM CELLS OP METAZOA. 



L65 



In the synapsis stage the fourteen chromosomes unite to form seven bivalent ones, 

 and the two chromatin nucleoli to Conn one bivalent chromatin nucleolus. The latter in 

 the stages following tins synapsis is rounded and peripheral in position (K 2, Fig. 48, 

 PI. FI), and only occasionally attached to the true nucleolus (2V). 



Pole views of the first maturation monaster (PI. II, Fig. 49) show eight chromatin 

 segments, of which one easily distinguishable from the others by its smaller size is the 

 chromatin nucleolus (N. #). Lateral views of this stage show that all eight of these 

 elements are bivalent and dumbbell-shaped. 



9. Perillus confluem I F. 8. 



Two testes of this species were examined. 



The rest stage of the spermatogonia (PL II, Fig. 50) shows two small, rounded 

 chromatin nucleoli of unequal size, which are always attached together, and may be 

 either close to the nuclear membrane or apposed to the surface of a true nucleolus (N). 



In the monaster stage of the spermatogonic divisions are sixteen chromatin segments 

 (Fig. 51). The fourteen largest are chromosomes, the two smallest are chromatin 

 nucleoli (N. 2); the latter are more minute than in the corresponding stage of any other 

 Pentatomid examined by me, and oil account of their small size cannot always he seen 

 (i, c, in cases where they arc closely apposed to the chromosomes). 



In the synapsis stage the fourteen chromosomes unite to form seven bivalent ones 

 and the two chromatin nucleoli to make one bivalent chromatin nucleolus. The latter is 

 dumbbell-shaped in the earlier stages of the growth period, but in the rest stage {N. 2, 

 Fig. 52) becomes oval in outline, and it is then attached to the surface of the larger (rue 

 nucleolus (N. 2), the two occupying a, more; or less central position within the nucleus. 



Pole views of the monaster stage of the first maturation division show eight- chromatin 

 segments of varying diameter (Fig. 53) '; one of these, probably the smallest, is the 

 chromatin nucleolus ; lateral views show that all these elements are bivalent and dumb- 

 bell-shaoed. 



10. Cosnus delius Say 



Three testes of Ibis species were studied. 



In the rest stage of the spermatogonia there are two chromatin nucleoli with irreg- 

 ular outlines (PI. II, Fig. 54, N. 2), and they are situated usually close together. 



In (lie spermatogonic monaster stage (Fig. 55) there are fourteen chromatin seg- 

 ments, the two smallest of which are probably the chromatin nucleoli (N. 2), leaving 

 twelve chromosomes; 



In the synapsis stage the twelve chromosomes unite to form six bivalent ones. The 



