60 ANATOMY AND PHYSIOLOGY 



gether, they get fastened to some stick or stone, 

 which retains them in a favorable condition for 

 the influence of solar heat. By what combina- 

 tion of circumstances the male is apprised of the 

 desire which the female has for expelling her bur- 

 den, cannot be explained : but it is nevertheless 

 true, that they commonly accompany her, and no 

 sooner are the ova deposited, than he swims over 

 them to complete the process. There is no ac- 

 quaintance between the parents : the male, in com- 

 ing in contact with the spawn, is excited by the 

 presence of the appropriate stimulus of the genital 

 organs, and a fluid is emitted over them, which, 

 though greatly diluted in water into which it is 

 infused, exerts a specific action on the egg, which 

 immediately begins to quicken into life. 



It may so happen, however, that the male of 

 another species accidentally in his wanderings, 

 comes in the region of roes — which excite him to 

 expregnate them, just as readily, as the presence 

 and contact of those of the family to which he be- 

 longs. The excitation effected by the eggs, can- 

 not be withstood, — for there are no moral re- 

 straints in the regions below, and physical necessi- 

 ty, absolutely, in this instance, forces into being, a 

 race partaking of the habits and characteristics of 

 the two progenitors. 



Sir Humphrey Davy says, " it is a fertile and a 



