64 BULLETIN OF THE 
ence of the peripheral layer of protoplasm that is divided into polygonal 
areas prior to the appearance of the blastoderm. 
Barrois (’78) added to what was already known an extended descrip- 
tion, with figures, of his so-called limuloid stage, and gave notes, without 
figures, on the development of the germinal layers. 
Balfour (’80) was the first to produce figures of actual sections to illus- 
trate the history of the germinal layers. Unfortunately, he had no 
material for the preblastodermic period. 
Sabatier (81) contributes notes on the formation of the blastoderm, 
and also on the yolk nucleus of spiders’ eggs. 
Schimkewitsch (84) offers the latest contribution to the subject in a 
preliminary notice in the Zoologischer Anzeiger for August 18, 1884, 
which embraces notes on the entire development. 
I.—The Egg. 
The eggs of Agelena novia are very abundant in the autumn. Those 
for the present study were obtained near Cambridge, Mass., from Sep- 
tember 15 to October 15. They exist in cocoons of white silk attached 
to the underside of fence boards or loosened bark, and in other sheltered 
places. This species, as well as others, continues to deposit eggs in 
captivity, thus furnishing a ready means of obtaining freshly laid 
material. 
Treatment. — For observations on fresh material the long-used method 
of immersing the eggs in oil is indispensable. The oil should be per- 
fectly clear and scentless. In hardened eggs the external features can be 
studied to great advantage by mounting in alcohol after they have been 
shelled and stained ; the structures previously obscured by the chorion 
thus become properly exposed. Before using this method I was unable 
to trace the “rudimentary terga.” Another valuable method for surface 
study consists in clearing the already stained egg in clove oil. I have 
found this especially applicable in determining, by means of optical 
sections, the thickness of the blastoderm on entire eggs. 
In the important work of preparing eggs for cutting, experiments were 
made with several reagents. The most satisfactory method of treatment 
proved to be the very simple one already long in use. The eggs were 
heated in water to about 80° C, and cooled slowly, after which they were 
passed successively from weak to stronger grades of alcohol. 
Good results were also obtained with Perenyi’s fluid, which renders the 
yolk less brittle, but at the same time changes somewhat its characteris- 
