426 J. E, BLOMFIELD. 
From this it will be seen that he recognises the cell which 
is formed at the base of the Spermatogemme as being part 
of the original cell which has been left behindin the growth 
and multiplication of the others, but he does not appear to 
recognise the similarity between this cell and those which 
are found in the Spermatogemme or Samenkugeln of the 
frog which is formed in the same way, and has a similar 
function. 
In Semper’s “ Monograph on the Urogenital System in 
Elasmobranchs” (‘Semper’s Arbeiten,’ Bd. ii), he gives an 
account of the development of the spermatozoa. The section 
of a mature ampulla, with its bundles of spermatozoa, is 
very like that of the frog; each bundle is connected with a 
nucleated mass which rests on the wall of the ampulla, and 
which he calls, from its protective function, ‘ Deckzelle,” 
though he recognises it as being the remains of the Mut- 
terzelle. He traces the fate of these bodies after the sperma- 
tozoa are shed, and finds that they undergo fatty degenera- 
tion, the nuclei fall together and are only held together by 
a granular detritus, while the ampulla itself collapses. This 
he compares to the formation of the corpus luteum in the 
ovary. In Elasmobranchs there is a continuous development 
of spermatozoa in the testis from within out, so that we get 
degenerated ampulle, full ampulle, ampulle with sperma- 
tozoa developing, and the formation of ampulle in the same 
testis, not coming as in Rana in successive crops from the 
same ampulla. The spermatozoa do not develop as in Rana 
from vesicles (hollow polyplasts), but on a plan more like 
that of the snail. He calls the young immature sperma- 
tozoa spermatoblasts, and says that he was unable to make 
out the origin of the tail. 
Klein, in his ‘Atlas of Histology,’ gives an account of 
spermatogenesis based on researches on man, rabbit, mouse, 
&c. In the contents of the seminal tubules he recognises 
two kinds of cells, the inner and outer seminal cells. The 
latter present two kinds according to the state of the 
nucleus; in one kind the nucleus is finely granular, in the 
other it is devoid of a limiting membrane, and has rods or 
filaments twisted in many directions in its interior. 
Nearer the lumen of the tubule are the inner seminal 
cells, which are seldom limited to one or two layers. They 
do not directly touch each other, but are joined by an 
‘interstitial substance. These cells are polyhedral from 
mutual compression, and their nuclei are similar to the 
second type of the outer seminal cells, that is, they contain 
rods or filaments variously arranged. Their nuclear rods 
