EGGS OF DOG- WINKLE. 47 



ing the dye, which afterwards became so famous. I 

 have elsewhere 1 recorded my own experiments oil the 

 stain yielded by the Purpura before us, with the 

 remarkable changes through which it passes before the 

 sunlight fully brings out the colour. The use of 

 cochineal makes us independent of molluscan dyes, 

 and the matter is merely one of antiquarian interest, 

 or a question of zoological chemistry. 



Perhaps you may be more interested in the develop- 

 ment of the Dog-winkle. Under the ledges of rocks 

 we find in abundance groups of little yellow bodies, 

 resembling ninepins in shape, set on their ends in close 

 contact with each other, and varying in numbers from 

 three or four to a hundred or upwards in a group. 

 Some of them are tinged with purple at the tips ; and 

 while sometimes you find them closed, and full of a 

 yellow creamy substance, at others they are open at the 

 top, and empty. 



These are the egg-capsules of this mollusk, and some 

 very unusual circumstances connected with the birth of 

 the progeny, and their development within these cases, 

 have been discovered by Dr. Carpenter. 2 Each capsule 

 contains 500 or 600 globules that cannot be distinguished 

 from each other at first ; but only twelve to thirty of 



1 See Devonshire Coast, p. 60. 



2 Trans. Micr. Soc. (Ser. II.), vol. iii. p. 17. 



