398 M. Victor Faussek on the Anatomy and 
were laid in autumn, at once commenced to develop at the 
temperature of an ordinary room, and within one and a half 
to two months the whole cycle of development was com- 
pleted, and the young animals emerged and throve perfectly 
well throughout the entire winter. The ova of Opilio parie- 
tinus perished under the same conditions, and were capable of 
further development only after passing the winter in a normal 
state, when I placed them upon the ground. Besides these 
two species I also had a few ova of larger size belonging to 
a species which I failed to determine. 
2. With regard to reagents, Flemming’s mixture gave the 
best results, in addition to Perenyi’s fluid and sometimes (for 
the earlier stages) hot absolute alcohol. I did not study the 
formation of the segmentation nuclei. The earliest stages 
which I examined showed the ovam divided up into a com- 
pact mass of cells; in each of the large segments there lay a 
large nucleus (Taf. i. figs. 6 and 7 of the Russian memoir). 
The ovum consequently undergoes total segmentation and 
passes through a morula stage. he first blastoderm (ecto- 
derm) cells split off from the superficially situated blasto- 
meres, as is correctly described by Henking*, The segmen- 
tation nuclei do not come to the surface of the ovum, but all 
remain within the blastomeres, In the Araneide, as may be 
gathered from the investigations of Morin }, total segmen- 
tation also takes place and the ova pass through a bDlastula 
stage, having a large segmentation cavity. In Phalangium 
a solid morula is formed, and the ectoderm cells are produced 
by being split off, as it were, by delamination. 
3. The entire ovum gradually becomes clothed with a 
layer of flat ectoderm cells, and thus passes into the bilaminar 
stage. After the formation of the ectoderm the inner ege- 
membrane (oolemma) becomes considerably thicker, so that 
two layers can be distinctly distinguished in it, which, how- 
ever, are closely apposed to one another and never separate. 
There is an evident secretion of cuticular substance by the 
ectoderm cells, which gives rise to the formation of a kind of 
embryonic membrane; yet this new cuticular membrane does 
not form an independent envelope, but serves to thicken the 
oolemma. ‘This subsequent secondary thickening of the 
membrana vitellina by the formation of a new cuticular layer 
secreted from the ectoderm is comparable to the formation of 
* Henking, “ Untersuchungen iiber die Entwicklung der Phalangiden,’’ 
Zeitschrift f. wiss. Zoologie, 45 Bd. 
+ Morin, “ Ueber die Entwicklung der Spinnen” (in Russian), Zeit- 
schrift der Neurussischen Gesellschaft in Odessa, xiii. Bd. (1888). 
