102 OYSTERS, AND ALL ABOUT THEM. 



oysters The ovaries of all were slightly dis- 

 tended, and full of spawn of various sizes .... 

 when seen in the microscope under a inch power. In the 

 smallest I could not perceive any motion ; but in the larger 

 I could distinctly detect the vibratile cilia or feelers, as they 

 would probably be termed by the fishermen, in active 

 motion. The smaller ones were round, with a dark mar- 

 ginal rim, and some had indistinct lines radiating from the 

 centre towards the margin : the larger ones were similar in 

 shape to those obtained from Loch Ryan on the loth of 

 July, 1856, and exhibited to the British Association at 

 Cheltenham : the interstices between the branchiae and 

 mantle were closely examined, but not a vestige of an 

 ovum was to be seen." 



In a footnote he says : " The spermatozoa with cilia 

 are, I should suppose, undoubtedly the perfect young ; but 

 what are the other rounded bodies ? A few having been 

 found with radiating lines, it appears likely that a sub- 

 division takes place in an early stage, probably after fecun- 

 dation. I did not see any. spermatozoa that I could con- 

 strue into male spermatozoa ; but I think it probable that 

 they might be visible in the early part of the year, before 

 the ovary begins to swell much." 



" The oysters opened were from z^ inches to 3 inches in 

 diameter, and had the smooth shell of ' natives ;' those 

 most advanced towards spawning had the margins of the 

 branchiae and mantle blackish, the others were of the usual 

 colour of oysters in season. I placed some of the spawn 

 freshly taken from the ovary in salt water, made after 

 Gosse's receipt, in a glass tube : they gradually sank to the 

 bottom, but at first appeared lively. 



"May 23. Received some oysters from Llandudno, in 



j *J * 



Caernarvonshire : they were of very large size, measuring 



