100 OYSTERS, AND ALL ABOUT THEM. 



rate authorities, is a crime, exposing the delinquent to the 

 penalty of transportation, (b) But the oyster has no such 

 power to attach itself to the rock ; it is utterly unable to 

 spin a thread. The common cockle digs its way into the 

 sand, and there finds a home ; but the oyster has not the 

 curiously-formed foot with which its neighbour gains 

 security from its foes. Yet it has all that is really neces- 

 sary for its safety, for it can emit from its shell, young as it 

 is, a calcareous and adhesive substance which holds it fast 

 to the rock, where it continues to live and grow during 

 successive months. (<:) 



The opinions of authors as to the mode of reproduc- 

 tion in the oyster may be divided into three : the first and 

 oldest is that of Ulysses Aldrovand, who, under the head 

 Generation, wrote as follows : " Ostreorum ortus causa 

 putredo qiiaedam esse videtur." With this quotation I 

 think we may at once dismiss the theory of putridity, from 

 which our old author supposes the oyster to be born, 

 merely mentioning that several others of the old writers 

 were of the same opinion. 



That mollusca are produced from ova appears to have 

 been the discovery of an anonymous writer in the " Philo- 

 sophical Magazine, 1603," who states that he saw the 

 young snails issue from their eggs, and that he was afraid 

 to give publicity to his discovery without the testimony of 

 other witnesses. This position, however, namely that 

 mollusca are produced from eggs, is not likely to be dis- 

 puted in the present day. 



The form which the young assume before quitting the 

 ovary is a question to which I shall have to refer again ; 



(b) Daniell's " Rural Sports." 

 (c) "Adventures of an Oyster." 



