360 
ORESSWELL SHEARER. 
eggs are remarkably granular and usually break badly when 
sectioned. They are also difficult to handle, and the only 
successful method of doing this is to attach them to pieces 
of liver as soon as they have been fixed, and then run them 
through the solutions. In this manner they are not lost, 
and can be readily cut in numbers in small blocks. My 
investigation of these stages has been very slow on account 
of the difficulty I have experienced in obtaining the eggs 
in numbers. The females do their egg-laying at night or in 
the early hours of the morning, and the maturation stages 
are quickty passed through once the eggs are deposited in 
the sea-water ; for this reason it is difficult to obtain large 
numbers of eggs showing the actual extrusion of the polar 
bodies. 
In view of the peculiar nature of the male and female eggs 
of D. gyrociliatus, great interest attaches to the investi- 
gation of the maturation divisions, but although I have 
devoted a great deal of time to the matter, I have been 
unable to decide many points with regard to the exact 
number of chromosomes extruded, on account of lack of 
sufficient material. I have been unable yet to obtain 
sections of the extrusion of the second polar body in the 
female egg , and until recently, I have been in considerable 
doubt as to whether a second polar body is given off by 
this egg. In my preliminary paper ( 17 ) I have suggested 
that only one is given off and that the second is simply 
derived from division of the first. I have, however, since 
established the fact that two are given off by the female 
egg, but as yet I have not obtained the second in sections. 
My knowledge, therefore, of the maturation divisions is 
incomplete in one important respect. This is the case also 
with regard to several stages in the formation of the chromo- 
somes after the extrusion of the polar bodies, my series not 
being consecutive. 
In the absence of any knowledge of the number of chromo- 
somes that go out in the second maturation division in the 
female egg, it is impossible to consider their significance with 
