Be. AR 
(3) Origin of Each Part of the Spermatozoon. 
The nueleus varies greatly in size and shape in the different 
groups. In Antedon rosaceus, and the Echinids, it is conical 
and comparatively small. In the Holothurids, Ophiurids, and Asterids 
it is in general nearly spherical or more often spheroidal, and ge- 
nerally considerably larger than in the Echinids. At the anterior 
end, usually at the apex, is a cupshaped depression, in which is the 
sperm centrosome. Those reagents, acetic acid, chloride of manganese, 
etc. which cause a swelling of the nucleus, diminish the size of this 
depression and consequently the centrosome is crowded out, and so 
projects more prominently above the surface. 
The chromosomes, 8 or 9, are easily seen by use of SCHNEIDER’S 
acetic carmine, acetic methyl green, safranin; etc.; but not in all 
of the spermatozoa, probably only the immature ones. From study 
of both teased preparations, and of sections both of ripe testis and 
fertilized eggs I am led to agree that in the mature spermatozoa the 
nuclein is no longer in separate pieces (chromosomes), but is dissol- 
ved, so to speak, in the caryoplasma, and that after having, in the 
fertilization process, passed the relatively hard and compact outer 
zone of the cytoplasm of the ovum, the nuclein again takes the form 
of separate and distinct bodies (chromosomes). 
Apparently neither the nucleus of the spermatid nor of the 
spermatozoon contains the small granules, staining purple in a double 
stain of safranin and dahlia, which are seen in the nucleus of the 
spermatogone and spermatocyte. 
Centrosome. This other component part of the head of the 
spermatozoon early attracted my attention, and I have devoted much 
time to working out its history. Many of its characteristics have 
been referred to above; its dissimilarity to the nucleus, its position, 
etc. Its size varies very greatly in the different groups. Owing to 
its small size, about 0,3 « in Echinus microtuberculatus; 
0,5 u in Arbacia pustulosa; 0,66 « in diameter in Sphaer- 
echinus granularis, it appears to have been overlooked by 
‚those who in studying only a type of Echinoderm spermatogenesis 
have selected the Echinids. While very small in the Echinids and in 
Antedon rosaceus, it is comparatively large in the Holothurids, 
Ophiurids, and Asterids; e.g. 1,3 « in diameter in Holothuria 
Poli; Stichopus regalis; Ophioglypha lacetosa, and 
Asterias glacialis. In these species and also in Chaetaster 
longipes, and Cucumaria Planci, it can be seen in the live 
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