SOME PROBLEMS OF COELENTERATE ONTOGENY 497 
vouched for by Smallwood (’09). My present method in this 
particular is to imbed the material in paraffine as early as possible 
after reasonable time has been given for proper hardening and 
dehydration. ‘This imbedded preservation may apparently be 
indefinitely prolonged without detriment. But in my experience 
it is impossible to preserve material of this group for any consid- 
erable period in alcohol without having it suffer considerable 
deterioration. This is particularly the case with those cytologic 
factors of mitosis and allied features so important in modern 
problems of embryology. 
4. Staining. This, like the matter of killing and preserva- 
tion is one of much importance and of varying grades of diffi- 
culty, as it related to the problem under review. As in the pre- 
ceding, I had long since called attention to the extreme difficulty 
in the staining reactions of coelenterate material. This was most 
marked, in my experience, in the eggs of Eudendrium and Pen- 
naria. Others have also found similar difficulties with this phase 
of technique. G. T. Hargitt (09, p. 163) has recently devoted 
some attention to the subject, and my own results have been 
confirmed by those described in his paper. 
Difficulties experienced in my earlier work in Pennaria, and the 
later work on Clava, were such as to leave doubt, particularly 
in relation to the phenomena of maturation, leading me to con- 
clusions, tentatively adduced, which subsequent work has not 
‘confirmed, as shown by G. T. Hargitt (op. cit.) and Smallwood 
(09), and by facts herein described. 
OBSERVATIONS 
A. Pennaria 
Except for additional facts which have come to light in rela- 
tion to a species of Pennaria, the development of which has been 
hitherto unknown, no particular attention would be given to the 
subject in this connection. Since the issue of my detailed paper 
on the early development of Pennaria tiarella (’04), repeated 
observations on the living eggs have confirmed my previous 
