ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
525 
interest, as to the number of white blood-corpuscles in the human blood 
in twenty morbid states, such as perityphlitis, acute rheumatism of 
joints, typhoid fever, and anaemia. 
INVERTEBRATA. 
Mollusca. 
a. Cephalopoda. 
Notes on Nautilus.* — Dr. A. Willey figures a living nautilus, show- 
ing the way in which the ordinary tentacles adhere to a foreign body, 
while the pre-orbital and post-orbital tentacles have no such adhesive 
power, but remain erect beside the ocular bulb. The spermatophore 
sac is figured in situ at the dorsal base of the buccal cone. The author 
notes that Graham Kerr and Bela Haller seem to have overlooked 
Huxley’s description of the delimitations]of the coelome, and the position 
and features of the three openings leading from the pericardium into 
the visceral portion of the coelome. Of these openings Willey gives a 
figure. 
7. Gastropoda. 
Movements of Freshwater Gasteropod3.t — Dr. L. Car has corrobo- 
rated Simroth’s account of the gliding movements of Limnsea and similar 
forms. The important motor factor lies in the muscular undulations of 
the foot. To explain the peculiarities of this “ wave-play,” Simroth 
suggested a special Gerinnungshypothese, which Car cannot accept. The 
extension and forward movement of the longitudinal muscle-fibres, 
and thereby of the whole sole, is brought about by a peculiar combina- 
tion of the postero-anterior contraction and relaxation of the longitudinal 
and dorso-ventral muscle-fibres. The result can be accounted for only 
by the combined action of the two sets of fibres. 
Spermatogenesis of Snail.J — Mr. A. Bolles Lee finds in Helix 
pomatia that the basal cells (“ ovules males ” of Duval, “ blastophoral 
cells ” of Blomfield) are merely supporting and nutritive elements. 
Apart from the primordial cells and the spermatides, there are three 
categories of spermatogenetic cells, the spermatogonia and two genera- 
tions of spermatocytes. 
The division of the spermatogonia is first distinguished by a phase 
when the nuclear elements form a group of segmented loops, like the 
corolla of a flower. Between this and the equatorial crown stage, there 
is a remarkable phase in which the secondary segments are scattered 
without order in the nucleus. Perhaps there is some qualitative re- 
duction in this phase. 
The division of the first spermatocytes recalls Carnoy’s division with 
straight rods (a batonnets droits ) and Flemming’s heterotypic division. 
Its essential feature is the fusion into a single chromosome of the seg- 
ments produced by the longitudinal splitting of a primary nuclear 
segment. During this process there appear figures in rings, in ellipses, 
in balls grouped in fours ( Vierergruppen doubtless). But these tetrads 
* Quart. Journ. Micr. Sci., xl. (1897) pp. 207-9 (1 pi.), 
f Biol. Centralbl., xvii. (1897) pp. 426-38 (14 figs.). 
x La Cellule, xiii. (1897) pp. 199-278 (3 pis.). 
