1887] The Significance of Sex. 21 
olus is left outside as a paranucleolus. In ¢ the nucleolus is homogeneous. In d it 
has microsomata, which fuse to one “ nucleolus-nucleus” in e. Finally, in f the nu- 
cleolus has all the structure of the old nucleus of stage a 
nucleus now dissolves in the re PTY the eT as a “yelk nucleus.” 
G. 57. Nucleus of egg of Toxopneustes—Flem 
Fie 58, a7. Nucleus of egg ag Stee Reet aW, Z., a paranucleus 
appears, whose changes are as complex as those of pA nucleolus. Malus in 7 we 
have only a vesicle left. 
Fic. 59, a-f. Nucleus of egg of larva of Libe/ula—Valette St. George, A. m. A., 
ii te structure of the large nucleolus in ¢ reminds us of the entire nucleus of 
e ae ő. 
a-f. Nucleus of egg of Asteracanthion—Van Beneden, Q. J. M. S., xvi. 
E 2 stage of f is reported finally to disappear. 
Fic. 61, a-f. Nucleus of egg of Rabbit. 
Fic. 62, a-. Nucleus of Gonothyraca loveni—Bergh, M. J., v.—Multiplication 
of nucleoli Me division 
1G. 63, : acess of egg of Bat—Beneden and ee A- B. 
Fic. 6 Nais of egg of Anodon—Flemming, A. m. A., x.—A paranucleus is 
he a a-b. Nuclei of sexual cells (* primitive ova”) of Rana—Nussbaum, A. 
m. A. xviii.—a of male, 4 of female. Budding of the nucleus in ovigenesis nak 
` spermatogenesis at this stage is often reported. 
Fics. 66-93 illustrate the formation of the spermatozoon from the nucleus of the 
“ spermatid,” and points in its structure. 
Fic. 66. Antherozoids of Hymenophylium—Carnoy, p. 226.—a shows the lar; 
reticulate nucleus of the daughter-cell of an antheridium. In 4 the nuclei is elon- 
gating, curved, and at its smaller end the net-work of chromatin is changing to the 
diffuse state. In ď the pointed end protrudes from the cell and bears the locomotive 
cilia. This is homologous with the head end of a SS The cytoplasm is 
gradually utilized as pabulum by the antherozoid, the residue remaining stuck to its 
hinder end e (which is finished last), to be eos talk eave or thrown off as at f. 
Fig. 67. Spermatozoid of Anodonta ce Oy, p. 225. 
Fic. 68. Early stage of spermatozoid of Slamándik Fhentiiag e 
Fic. 69, a-b. Human spermatozoa, not yet freed from their matrix—Wiedersperg, 
A. m. Å., xxv. 
Fic. 70. Spermatozoid of Zlephant—Weidersperg, A. m. A., xxv.—The head and 
tail project from the cell, the “ neck” or “ middle” piece is still growing. In the 
cyt 
- paranucleus 
i. 71, a-e. ppermatoprai of Rat— Brown, Q. J. - = » July, 1085. ees nucleus 
difin 
ce 
er here also is a Aead- -corpuscle. At the opposite end is a tat/-corpuscle. In the cyto- 
plasm lies a paranucleus. 4 shows the fine axis of the neck and tail proceeding from 
near the ¢atl-eorpuscle. In c the whole nucleus has become homogeneous, elongated 
d curved, and mostly protruded from the cytoplasm. d shows the sperm. nearly 
apla a relic of cytoplasm remains sticking where the head and neck join, and 
another where the tail and neck join. The latter contains the remains of the para- 
nucleus (“seminal granules”). æ is the completed sperm. The neck shows 2 
ucture. 
Fi. 72, a-f. Sperm. of Bull—Kölliker, Z. w. Z., vii.; EA, Brunn, ek: 
