CYTOPLASMIC INCLUSIONS OF THE GERM-CELLS. 461 
formed, while on the left the mitochondria are still separate. At A.B. 
are two acroblasts. 
Fig. 15. — Spermatid, with centrosomes, micromitosome, macromito- 
some, acroblasts, and nucleus. At XI. the mitochondria have not yet 
completely run together, and there is no true spireme in the macromi- 
tosome. The nucleus lies towards the lumen of the spermatid group, 
and will have to travel around as it is doing in the next figure. 
Fig. 16. — Same stage as fig. 15, only the nucleus is nearer its goal. 
The acroblasts are nearly spherical. 
Fig. 17. — Nucleus in its definitive position. Centrosomes marked 
C l and C~, the latter now having passed towards the tail, not having a 
definite connection with the axial filament. The acroblasts are pressed, 
in part, between macromitosome and nucleus. Micromitosome at M. 
The outline of the neighbouring spermatozoa is drawn at X.Y. One 
acroblast has formed the acrosomic granule. 
PLATE 24. 
Figs. 18, 20, 21, 25, 26, and 28 drawn at the same magnification as in 
PI. 1. Fig. 29 is drawn to the same scale, but has been reduced by one 
half. All these figures are of S. populi. Figs. 19, 22, 23, 24, and 27, 
drawn at table level with camera, lucida and with a y^th Koristka semi- 
apocliromatic oil immersion and compensating eyepiece 18. Magnifica- 
tion, 4250. 
Fig. 18. — Spermatocyte of Smerinthus populi preserved over- 
night in strong Flemming, to show effect of the acetic acid. Nuclear 
matter has become resolved into chromosomes. The micromitosome 
(M.) is much swollen and is apparently about to divide ; the amphi- 
aster in is process of formation. (Compare with fig. 8, PI. 1.) 
Fig. 19. — Spilosoma lubricipeda preserved in strong Flemming 
without acetic acid. Spermatocyte near end of growth-period, from an 
“ apyrene ” group. The filaments terminate in the large clavate organ 
(C.O.). 
Fig. 20. — Spermatozoon of S. populi well advanced in meta- 
morphosis. Shows acrosome and granule (A.G.). 
Fig. 21. — Metaphase of spermatogonial division in S. populi, show- 
ing mitochondria ( M.D .) a micromitosome (M.), and the persistent 
nuclear membrane. 
Fig. 22. — Spermatocyte of Pier is brassicse at end of growth- 
period, showing various cell details. 
Fig. 23. — Young spermatozoon of Orgyia antiqua (Flemming 
with reduced acetic acid). 
VOL. 62, PART 3. NEW SERIES. 
32 
