550 Theophilus s. Painter, 



behaves as a planosome. During the first division the accessory- 

 chromosome lies outside of the general circle of autosomes, and this 

 body passes to one pole early in the metaphase. It is clearly made 

 up of two elements, as a glance at Fig. 95 will show. 



Second maturation division. 



In the second division the accessory chromosome divides. Seen 

 from equatorial view, the autosomes of this division lie well apart, 

 as shown in Fig. 96. After the autosomes have divided, we often 

 find lagging behind in the spindle one very small chromosome 

 (Fig. 96). This is probably the planosome which we found during 

 the growth period. 



Number of chromosomes. 



The haploid number of chromosomes is eleven, see Figs. 95 

 and 96. The chromosome formula would be then: 

 Autosomes 22 



Accessory chromosomes 2 



Total 24 excluding the planosome. 

 Three males were studied, only one of which showed the 

 presence of the planosome. In other respects the three specimens 

 were alike. 



Spermatogenesis of Annphaena saltibiinda. 



The behavior of the nuclear elements during the growth period 

 is the same as that found for Maevia vittata. It is interesting to 

 note that in the pachytene stage we often find two very small but 

 densely staining elements whicli probably represent planosomes. 



The spindle of the first division usually shows the accessory 

 chromosome as two rod-like elements lying in the usual position for 

 it (Fig. 99j. In equatorial view, the autosomes are arranged in a 

 general circle. Another rather constant feature of the equatorial 

 plate is the appearance of the small chromosome, marked "P" in 

 Fig. 99. 



During the early metaphase tlie accessory chromosome passes 

 undivided to one pole. I have not followed the course of the very 

 small chromosome during this division. 



The accessory chromosome divides during the second maturation 

 mitosis. After the autosomes have gone apart, we find as many as 



