664 
J. P. Munson 
pathological States of the egg, or is it an artefact due to reagents? 2. Is 
there a necessary connection between one form and another such that 
one can be derived from the other? 3. Is it an amorphous Chemical sub- 
stance or does it possess anything suggesting permanence of structure? 
4. Does it arise de novo or is it a modification of something similar exist- 
ing in the cytoplasm of the oogonium? 5. Does it arise from chromatin 
eliminated from the germinal vesicle? 6. Is it due to cells entering the 
egg? The answer to these questions will determine whether or not it is 
important. 
Material: — Fresh ovaries of tortoise, spider, king crab, pigeon 
goosefish, cat, crayfish, and frog. 
Methods: — Much experimenting has to be done before any results 
are obtained. The eggs of different animals require different treatment, 
and very often a new method has to be found for the successive stages 
of the same egg. In the matter of fixing, for instance, I find that the length 
of time is as important as the kind of fluid used. Different eggs, how- 
ever, differ greatly as regards the behaviour of the yolk nucleus towards 
reagents. In some cases, as in the spider, almost any hardening fluid 
will show the yolk nucleus well preserved, often though the germinal 
vesicle and the rest of the cytoplasm be badly fixed. Poorly preserved 
material sometimes shows normal features that cannot be made out so 
clearly in more perfect fixation. 
I have followed the plan of using much material and comparing 
results of different methods. In all those cases where astral rays are 
visible, the fixation has been most perfect. 
The preparations from which my drawings are made, were exhibited 
at the Eighth International Zoological Congress, Graz, Austria 1910; 
and I have taken special pains to have my slides examined by those com- 
petent to judge. I find that even those wlio are not specially trained in 
the use of the mieroscope, experience little or no difficulty in seeing what 
I have represented in my drawings. 
In the selection of types of animals for this study, I have nec- 
essarily been influenced by the ease with which the material could be 
procured. 
I am very thankful to the Librarian of the University of Christiania, 
of the University of Berlin, and of the Naples Zoological Station for the 
many kindnesses shown me in my efforts to verify some of the data in 
connection with the literature used in the historical part of this work. 
I am espeeially indebted to the Librarian of the biological library of the 
University of Chicago, and desire to express, here, my hearty thanks. 
