THE BRITISH COLUMBIAN OYSTER 131 



In size, colour, and flavour, the Pacific oyster is much inferior to the 

 Atlantic species, but in places (e.g. Oyster harbour) it is extensively col- 

 lected by the Indians, and may be seen on the markets of Vancouver and 

 other cities. 



Hermaphrodite Character. — A most interesting and important feature 

 of the Pacific oyster is its divergence in some respects from the mode of 

 breeding of the Atlantic species, and its resemblance in the same respects 

 to the common European species {Ostrea edulis L.). This is a most 

 fortunate circumstdnce, since it prevents any possibility of cross-fertilization 

 and inter-breeding between Atlantic and Pacific species, and permits our 

 most estimable Prince Edward Island oysters to be planted in British 

 Columbian waters without a chance of hybridization reacting to lower 

 their standard of superiority. In our western species their is no primary 

 separation into males and females — each oyster is like every other one, 

 or, as it is also stated, the sexes are united in each individual; other- 

 wise expressed, each individual is bisexual, hermaphrodite, or monoe- 

 cious. Our eastern species is exactly the reverse, being dioecious or 

 unisexual, i.e., every individual is either a male or a female. 



My first observations were made on July 12th, on specimens procured 

 under stones near the Biological Station. Nearly all appeared to be 

 males and, as they were of small size, I took it that, as commonly occurs, 

 the males had ripened first. But one was of medium size and contained 

 eggs, that at once attracted my attention on account of their large size 

 and opacity — the nucleus being rarely observable. Measured exactly 

 as all my former measurements they were: Oc. V, obj. 2=6.5; Oc. V. obj. 

 4=«15; Oc. V. obj. 7=72. Another individual procured a day or two 

 later, with an abundance of eggs, pure and ripe, oozing from the oviduct, 

 gave the almost unvarying measurement of Oc. V. obj. 7=75, which, 

 when calculated, is 75 x 1.45= 108. 75m = slightly over .1 mm. = slightly 

 over 1/250 inch, = fully twice the diameter of the egg of the Atlantic oyster, 

 and perhaps identical with that of the English or common European 

 oyster. 



Upon turning to the 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, irreg-ulai', 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 becoming spermatozoa. 

 One of these measured 46 x 40 ;w 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 spermatozoa on the surface. Between these 

 masses are millions of free, mature, swimming or moving spermatozoa, 

 of which the tails are rarely visible until they are looked for under a high 

 power. I have not made extensive measurements of the spermatozoa of 



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