THE DEVELOPMENT OF THE SPERMATOZOA. 425 
respects comparable to those found in the spermatogenesis 
of Helix. 
Kolliker (‘Zeit. fiir Wissen. Zool.,’ Bd. vii, p. 201) seems 
to have been the first to give a plan of spermatogenesis. 
He gives figures of developmental stages from the bull, 
pigeon, frog, and carp; at the same time noting that the 
account holds good for all animals. 
He believed that the spermatozoa were developed by a 
direct metamorphosis of the nuclei of the cells of the testis. 
This change takes place in what he calls “ Blaschen,” which 
are probably nothing more, as Meyer suggests, than poly- 
plasts modified by the fluid (Miller’s) with which he 
treated them. THe conceived that the tail as well as the 
body originated from the nucleus. 
He very shortly describes the process in the frog, but with 
the exception of the figures, which show well the bundles of 
spermatozoa united by the blastophoral cells, there is little 
agreement between my account and his. 
V. la Valette St. George has, in his fifth communication, 
“On the Development of the Spermatozoa,” to Max Schultze’s 
‘Archiv, Bd. xv, p. 261, given an account of sperma- 
togenesis in general. 
The paper commences with an exhaustive résumé of 
previous observations and papers published in connection 
with the subject, and then gives an account of the process 
as he has observed it in many Mammalia—bull, ram, stallion, 
rabbit, &c., and ends with a summary which embodies his 
ideas of spermatogenesis based on his former papers. He 
recognises in the testis tubule two kinds of cells. Of the 
first, he says, ‘* Peculiarly like young ovarian cells they are 
destined to multiply as Ursamenzellen or Spermatogonia ; 
in a similar manner by division and by transformation of their 
descendants (the Spermatocytes) they are destined to give 
rise to the’spermatosomes (Samenkorperchen). They pro- 
duce a mass of cells which either by an arrangement of the 
peripheral cells develop a special cover—Keimkugeln, Sa- 
menkugeln, Spermatocysten (Insects and Amphibia), or 
remains coverless—Samenknospen, Samensprossen, Sperma- 
togemmee, whilst the protoplasm which belongs to each cell 
is more or less segmented. In many cases one of the cells 
resulting from the division or its nucleus is preserved at the 
foot of the Spermatogemme.” 
“The second kind of cell which I call follicle cells are 
bound together into a tissue which, while it embeds the 
Spermatogonia, also covers and protects the Speratom- 
gemme in their multiplication by division.” 
