298 BOARD OF AGRICULTURE. 



from the egg of the quadruped. Aud so it is with the fish, 

 whatever be the kind of fish. I have examined many sharks 

 and skates, as well as many of our salmon and trout, and our 

 various kinds of suckers and cod-fish, and I know that all 

 these diiferent kinds of fish produce similar ovarian eggs. 

 Some of them lay them early, aud lay eggs which are at once 

 recoofnized as eggs, and others retain their eggs imtil the 

 young are fully developed and they bring forth then, like 

 the quadruped, living young ; so that they exhibit within the 

 limits of one and the same class diflTerences similar to those 

 which we observe among different classes in the higher ani- 

 mals. And if we pass from the class of fishes to the lower 

 types ofthe animal kingdom, — to insects, for instance, Crusta- 

 cea, and worms, — we find everywhere the same process. Even 

 the parasitic intestinal worms are now known to be produced 

 by eggs, and eggs which are transferred by various jDrocesses 

 from one animal to another, sometimes with their food or 

 drink, and thus become again parasitic in succeeding genera- 

 tions. The same thing has been observed among the various 

 kinds of molluscs, — the cuttle-fish and periwinkles, the oys- 

 ters and mussels, for all these produce eggs ; and when 

 the eggs are examined, at the proper time, and in a proper 

 manner, they exhibit exactly the same structure as those of 

 the higher classes ; and we may go down to the very lowest 

 class of animals — the sea-urchins, the star-fish, the jelly-fish, 

 or even the corals or polyps, and there again eggs are found, 

 and eggs which in no way difier from those of the higher 

 animals. 



From such statements, which cover now such extensive 

 ground, it might be inferred that to know one is equal to 

 knowing all. By no means ; but enough has been done to 

 show us that every one has its peculiarities, every one has 

 its own mode of development, and in every one there are 

 peculiar processes which make the generalization only true in 

 the most comprehensive form of expression, and no longer 

 true in the details of the farther development. So that all our 

 knowledge of the process of reproduction in one species of 

 animals, may not give us an answer when we would inquire 

 into the corresponding process in another animal. Thus 

 you see the necessity of repeating for those animals, the 



