No. 541] THE CANADIAN OYSTER 



37 



obj. 4 = 15; Oc. V, obj. 7 = 72. Another individual, ob- 

 tained since, with an abundance of eggs oozing from the 

 oviduct, pure and ripe, gave the almost unvarying meas- 

 urement of the egg as: Oc. V, obj. 7 = 75. This when 

 calculated is 75 X 1-45 = 108.75 ^ = slightly over .1 

 mm. = slightly over !4-,o inch = fully twice the diameter 

 of the egg of the Atlantic oyster, and perhaps identical in 

 size with the egg of the English oyster. 



In making measurements it is important to use only 

 ripe eggs, as in this ease, and to select those that are 

 spherical or nearly so and not flattened by the weigth of 

 the coverslip, as well as to extend the measurements to 

 many individuals in order to exclude all possibility of a 

 slip. The nucleus is between one half and two thirds 

 the diameter of the egg. 



Upon turning particularly to spermatozoa I found 

 them in every individual— even between the eggs of those 

 containing eggs in the gonad. The younger individuals 

 had no ova, but all sperms. Some of the older ones had 

 a few big, soft, opaque, irregular, elliptical, oval or 

 nearly spherical eggs, scattered among irregular masses 

 of less than half their size, which are balls of spermatids 

 on the way to development into spermetozoa. One of 

 these measured 46^X40/*, and each one is kept in a 

 dancing or rolling movement, somewhat like that of many 

 infusoria, by the flapping of the tails of the ripening 

 sperms on the surface. Between these masses are mil- 

 lions of mature, free, dancing spermatozoa, of which the 

 tails are rarely visible until one searches for them with 



ful, while at other parts there are only sperm-balls. 



