ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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72 hours ; and Mantegazza states that ho kept human spermatozoa at 
0° C. for 4 days without their losing their vibratile powers. Mr. Piersoll 
kept preparations at a temperature of 7-8° C. for as long as 8 days 
10 hours, after which some of the elements displayed feeble movements 
at a temperature of 25° C. In another preparation, kept for 9 days 
9 hours at a temperature of 8*5° C., a few of the elements exhibited 
well-marked motion after being placed in 25° C. for an hour. The 
capability of moving was more persistent in those cases in which vibra- 
tion was temporarily arrested from time to time by reduced temperature, 
for in control preparations kept continuously at 21° C. the motion con- 
tinued to the end of the fourth day and then stopped. These facts 
suggest that the male elements may long retain their vitality in the 
female generative tract ; and they are also of interest in connection with 
certain medico-legal questions. 
Development of Amphioxus.* — Herr B. Lwoff finds that his results 
do not in all respects tally with those of Hatschek. According to 
Hatschek, the longitudinal axis of the gastrula crosses that of the blastula 
at a sharp angle, and the asymmetry is partly explained by the activity 
of the endoclerm as contrasted with the ectoderm. According to Lwoff 
there is no cessation of division on the part of the ectoderm, mitoses 
being most frequent in the future dorsal surface of the gastrula and at 
the margin of invagination. At the margin of invagination the single- 
layered nature of the epithelium is lost. In short, the invagination is 
due to the continuance of the more rapid — especially dorsal — multipli- 
cation of micromeres, which are invaginated dorsally, forcing the proper 
endoderm cells to lie on the floor and sides of the cavity. This dorsal 
invagination of ectoderm is a cenogenetic process which has to do not 
with gastrulation, but with the formation of the notochord and meso- 
derm. In Amniota the palingenetic gastrulation proper becomes sub- 
ordinate ; the cenogenetic “ ectoblastogenic invagination ” becomes 
more prominent. As to the pole-cells which Hatschek believes to form 
the posterior mesoderm, Lwoff cannot after careful searching find them. 
The formation of the mesoderm folds is not an active invagination, but 
is due to the sinking down of the medullary plate. Lwoff will not 
admit that they are simply diverticula of the archenteric wall, nor even 
that their cavities form the body-cavity. For (1) the dorsal wall of 
the archenteron is not like the ventral wall, as above explained, and 
(2) the cavities of the fold disappear in each primitive segment, subse- 
quent divergence of cells forming the true cavities. In short, Amphioxus 
is, after all, not an example of enterocoelic formation of a coelom. The 
notochord arises from the “ ectoblastogenic ” rudiment, though endoderm 
cells perhaps help. The connection of notochord and endoderm is at 
least secondary. Herr Lwoff promises further details in support and 
extension of his somewhat upsetting conclusions. 
Inheritance of Modifications, f — Mr. J. A. Ryder treats of the 
inheritance of modifications due to disturbances of the early stages of 
development, especially in the Japanese domesticated races of Gold-Carp. 
The evidence now before him compels him to withdraw his previously- 
* Biol. Centralbl., xii. (1892) pp. 729-44. 
f Proc. Acad. Philadelphia, 1893, pp. 75-94. 
1893. Y 
