No.401.] DEVELOPMENT OF PENNARIA TIARELLA. 389 
from eelgrass, piles of the Fish Commission docks, and from 
fucus and rocks in the shallowed waters in and about the rocky 
outlet of the * hole." Material specially for the developmental 
work was usually collected, when convenient, during the later 
afternoon, so that no considerable time should elapse before 
the discharge of the eggs. When by reason of tides this was 
not practicable, collections were made at other hours, and the 
material placed in floats off the exposed sides of the docks, 
where conditions of water, temperature, etc, would be as 
nearly normal as possible. Experiments, however, showed 
that this precaution was not essential, no apparent differences 
being distinguishable between collections brought to the labor- 
atory aquaria and those floated outside. 
For killing and fixing, many methods were tried, but without 
that marked preferential distinction for one or a few which is 
often found for other material. Almost any of the standard 
fixing agents will give fairly good results. If any preference is 
assignable, I should give it to the stronger solutions of Klein- 
enberg's picro-sulphuric acid, or picro-acetic, in which the 
acetic acid was often used in a solution as strong as IO per 
cent. The various corrosive solutions gave results of about 
equal value, and for carmine staining was specially good. 
Perenyi’s fluid gave fairly good results, though less certain 
than the others. Flemming’s fluid, while affording admirable 
fixation, rendered subsequent staining so difficult as to make 
its value secondary. 
For surface study of the eggs, out of a very large number 
of experiments with numerous staining agents, only one gave 
results of sufficient value to be worth record, namely, Conklin’s 
picro-sulphuric-haematoxylin, and this, when compared with 
results upon such eggs as those of Mollusca, was quite infe- 
rior, though enabling one to distinguish definitely considerable 
of the internal organization of the egg from surface views. In 
no other egg, save that of Eudendrium, have I found such dif- 
ficult material from which to secure even approximately good 
differential staining reactions. Whether this is due to some 
physiological condition peculiar to these eggs, or to their pecul- 
iar opacity, I am unable to say. 
