MUNSON: SPERMATOGENESIS OF PAPILIO. 
103 
i 
12. In the later larval and adult stages, the primary spermato¬ 
gones can be found only in the immediate neighborhood of the 
grandmother stem cell. 
13. The primary spermatogones divide and form secondary sper¬ 
matogones to the number of one hundred and fifty cells contained in 
a cyst. 
14. The cortical nucleus constricts off with the primary sperma¬ 
togone, divides by mitosis once or twice, and gives rise to the cyst. 
15. In the spermatocyst stage, one of the cyst cells develops into 
a large head nurse-cell, in the body of which the heads of the mature 
spermatozoa are imbedded. 
16. The various stages of development of the sperm cell can be 
traced in their regular order only by choosing a grandmother stem 
cell as the starting point, thus: (a) grandmother stem cell, (6) mother 
branch cell, (c) cortical nuclei, (d) primary spermatogone, (e) 
gonocyst, (/) cytocyst, (g) spermatocyst. 
17. In those follicles having no grandmother stem cell, the above 
series cannot be found, as the primary spermatogone is here wanting 
and no new ones are produced. 
18. The grandmother stem cell gives rise to new spermatogones, 
and consequently even late in the season, new spermatogones are pro¬ 
duced. 
19. This butterfly is sexually mature in the pupa state a month or 
two before the last molt. 
20. The secondary spermatogones are spherical and fill the gono¬ 
cyst. 
21. Near the end of the period of multiplication, probably just 
before the last spermatogone division, the spermatogones become coni¬ 
cal with the large nucleus at the broad external pole. 
22. The chromatin becomes massed at the inner pole of the nucleus 
leaving the remainder of the nucleus a large vacuole. It seems to 
correspond to the synapsis of writers, but nothing indicates the pseudo¬ 
reduction generally attributed to it. 
23. After synapsis the chromatin fills again the nuclear vacuole, 
and appears now as a very delicate loose network of straight inter¬ 
secting fibers. This is preceded by a spireme. 
24. From this nucleus, there is developed a spindle with all the 
chromosomes arranged very regularly in the equatorial plate. The 
chromosomes split, form a diaster, and in the anaphase move simul- 
