430 J. E. BLOMFIELD. 
and assume an oval form. The next stage consists in a 
multiplication of this nucleus, apparently by its breaking up 
and a reappearance of the pieces in two or three places, pro- 
ducing a corresponding number of nuclei. By a repetition 
of this process the Spermatogemme is produced (figs. I—29, 
Taf. i). These bodies he regards as fundamentally a collec- 
tion of several cells, and in support of this view adduces the 
fact that a single spermatocyte may run its course to a 
mature spermatozoon without presenting this form, never 
possessing more than one nucleus. ‘These bodies have a 
radial arrangement in the testicular tubule and an elongated 
shape from the pressure of the surrounding cells, but they 
are generally spherical when isolated and floating free in a 
liquid. 
The last stage is the change of the nucleus to form the 
head and the division of the plasma of the Spermatogemme 
into tongue-like processes which form the tail. The first 
ehange varies according to the animal examined, that is, to 
the shape of the spermatozoon head. He regards the middle 
piece as derived not from the nucleus, but from the plasma. 
The rest of the plasma which has taken no part in the for- 
mation of the spermatozoa remains behind for a time to 
support them, but finally undergoes a kind of fatty degene- 
ration. 
He recognises the existence of v. Ebner’s spermatoblasts 
under the name of “ Samenahren,” and says that “ interme- 
diate forms may be seen from the spermatocyte to the mature 
‘Samendhren’ connected with the Ursamenzelle, to which 
they owe their origin, by a process of plasma (figs. 35, 36, 
38, 40).” 
He disagrees with v. la Valette St. George in thinking 
that the interstitial cells do not multiply at the same time 
as the Ursamenzellen, and form layers round the spermato- 
cytes and Samensprossen as the last named observer does. 
From this account it will appear that his Samenahren 
are the bases of v. Ebner’s spermatoblasts, and correspond 
to the cell which is left at the foot of the Spermatogemme 
described by v. la Valette St. George. 
The foregoing papers of which I have given an account 
are few out of many, but they embody the results of those 
which I have not mentioned, and taking into consideration 
the facts and drawings given in them it seems possible to 
reconcile to a large extent the different accounts of sperma- 
togenesis in mammals in the following short résumé, 
omitting as far as possible the particular terms used by each 
author. ‘The wall of the testis is lined on the inside with a 
