61 



PROCESS OF DEVELOPMENT IN FISHES. 



In leaving these slight anatomical sketches, and 

 turning to the more interesting field of Physio- 

 logy, we shall first direct attention to the different 

 methods by which the grand process of reproduc- 

 tion is regulated in fishes. The last part of Pro- 

 fessor Midler's admirable treatise on Physiology 

 having appeared within these few months, in which 

 such a flood of light is thrown upon the subject 

 of development, we cannot lose this opportunity of 

 recommending it to the attention of all who are 

 curious in the astonishing secrets of Nature's work ; 

 and, still more to enhance this recommendation, we 

 shall endeavour, in a few paragraphs, to supply a 

 specimen of the information which may be gleaned 

 from his original and philosophical pages. 



The process of the development 6f the ova of 

 different animals appears to be exhibited under three 

 distinct forms. First, in Oviparous animals, the 

 ova are expelled from the system of the mother, and 

 undergo development independent of it, the requi- 

 site nourishment being contained within themselves. 

 Secondly, in other instances the ova are developed 

 within the body of the parent, where they lie free, 

 for a time, in some part of the oviduct, with which 

 however they have no organic connexion. In this 

 case, as in the former, they derive no nourishment 

 directly from the parent, although some of the fluid 

 with which they are sui rounded may be appropriated 



