304 LANGENBECK. [VoL. XIV. 
the egg. It was, therefore, found advisable to dissect off the 
chorion, since it collapses when the egg is placed in oil of 
cloves, and the resulting folds in it are easily mistaken for 
cleavage furrows. 
The eggs were overstained in Kleinenberg’s or Delafield’s 
haematoxylin, washed out with acid alcohol, dehydrated, cleared 
in oil of cloves, and mounted under a cover slip supported by 
wax feet. By pushing the cover slip from side to side the eggs 
could be rolled into any desired position while they were being 
studied. Mlle. Rossiiskaya attempted to work upon the whole 
egg viewed as a transparent object, but says that she met with 
no success. I found that, unless a strong condensing lens is 
used, it is, as Mlle. Rossiiskaya ('88) says, almost impossible 
to distinguish the cellular structure, but with the condensing 
lens the cells can be distinctly and clearly seen. These same 
eggs which had been studied zz toto were then imbedded in 
paraffin and sectioned. It was not possible to cut the seg- 
mentation and early blastoderm stages thinner than 10 y, be- 
cause the protoplasm at this time is so distributed that it does 
not seem to offer sufficient support to the yolk. Sections of 
the later stages were cut 5 u thick, and preferably stained upon 
the slide. Eggs of the third day and after, when the yolk was 
partly digested, were stained with a %% aqueous solution of 
haematoxylin and washed out in iron alum, according to the 
usual iron-alum method. This stain could not be used for the 
earlier stages, because the undigested yolk becomes very black 
and totally obscures the structure of the egg. 
I tried to orient the eggs for sectioning according to Patten’s 
method. They were so small, however, that the least amount 
of celloidin which would hold them to the paper formed a 
coat over the eggs so that the paraffin did not penetrate. 
Knowing the relative position of the dorsal organ with respect 
to the rest of the embryo, from a study of the cleared egg, it 
was not difficult to orient sections. 
