tnci. 



/in 



Figure 297- 



- Mature spermary of C. virginica. ind — indiflferent cells; spg' and spg- — primary and secondary spermato- 

 cytes; spt — spermatids; spz — mature spermatozoa. Redrawn from Coe, 1932a, fig. 8. 



secreted by the egg itself while it is still in the 

 ovary. Raven (1958) states that in some cases 

 the vitelline membranes of Ostrea, Alytilus, 

 Dreissensia, and Dentalivm are thrown off soon 

 after shedding. I have not seen this happen in 

 the eggs of C. virginica. 



CYTOPLASMIC INCLUSIONS 



Cytoplasmic components of an oj'ster egg are 

 not well known primarily because the ultrastruc- 

 ture has not been studied by electron microscopy. 

 Certain types of minute granules can be seen, 

 however, in examination of live eggs under liigh 



magnification of phase contrast lenses; by applying 

 vital and metachromatic stains; by centrifuging 

 whole eggs or their homogenates in order to sepa- 

 rate various components and study their staining 

 reactions. For descriptions of the techniques 

 used in modern cytology the reader is referred to 

 the textbooks on cytology and microscopic histo- 

 chemistry (Gomori, 1952; DeRobertis, Nowinski, 

 and Saez, 1960; and others). The yolk constitutes 

 the major part of the eggs of marine bivalves. 

 Quantitative data on the amount of yolk in oyster 

 eggs are lacking, but for fumingia teUinoidex and 

 MytiluK californianus Costello (1939) found that 



328 



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