94 ZOOLOGICAL PHILOSOPHY 



as buds or internal gemmules ; they establish a connection between 

 internal gemmiparous reproduction and sexual oviparous reproduction. 



The strength of habit is so great that man always perseveres in the 

 same view of things, even when it is contrary to the evidence. 



Thus botanists, accustomed to observing the sexual organs of a 

 great number of plants, affirm that all without exception have such 

 organs. Consequently several botanists have made every conceivable 

 effort to discover stamens and pistils in cryptogamic or agamic plants ; 

 and they have preferred to attribute arbitrarily and without proof 

 these functions to parts of whose use they are ignorant, rather than 

 admit that nature may attain the same end by different means. 



It was believed that every reproductive body is a seed or egg, that is 

 to say, a body which must undergo the influence of sexual fertilisa- 

 tion in order to be reproductive. This is what caused Linnaeus to 

 say : Omne vivutn ex ovo. But we now know well plants and animals 

 which reproduce entirely by means of bodies that are neither seeds 

 nor eggs, and which consequently do not require sexual fertilisation. 

 These bodies are therefore differently fashioned and develop in another 

 manner. 



The following is the principle to be observed in judging of the method 

 of reproduction in any hving body. 



Any reproductive corpuscle which without having any investment 

 to break through lengthens, grows and becomes a plant or animal 

 similar to that from which it sprang, is not a seed nor an egg ; it 

 undergoes no germination and does not hatch after beginning to 

 grow, and its formation requires no sexual fertilisation : thus it does 

 not contain an embryo in an investment which has to be broken 

 through, as does the seed or egg. 



Now, if you follow attentively the development of the reproductive 

 corpuscles of algae, fungi, etc., you will see that the result of the lengthen- 

 ing and growth of these corpuscles is to take imperceptibly the shape 

 of the plant from which they spring ; that they do not break through 

 any investment as does the embryo in the seed or egg. 



Similarly, if you follow the gemma or bud of a polyp Uke a hydra, 

 you will be convinced that this reproductive body does nothing but 

 lengthen out and grow ; that it breaks through no investment ; in short, 

 that it does not hatch hke a chicken or silkworm coming out of its egg. 



It is then clear that all reproduction of individuals does not come 

 about by means of sexual fertilisation ; and that when sexual fertilisa- 

 tion does not occur there is not really a true sexual organ. Now as no 

 organ for fertilisation is to be distinguished in the four classes follow- 

 ing the insects it appears that this is the point in the animal chain 

 at which sexual reproduction ceases to exist. 



