44 deCtENeeation : i 



that no such a thing as an Ascidian tadpole existed, 

 but that the Ascidian's egg grew as directly as possible 

 into an Ascidian, in every living species of the group. 

 This might easily be the case. Then most assuredly 

 we should not have the least notion that the Ascidians 

 were degenerate Vertebrates. We should still class 

 them where they used to be classed before the Eussian 

 naturalist Kowalewsky discovered the true history and 

 structure of the Ascidian tadpole. I believe that I 

 shall have the assent of every naturalist when I say 

 that the vertebrate character of the Ascidians and the 

 history of their degeneration would never have been 

 suspected, or even dreamed of, had the Ascidian tad- 

 poles ceased to appear in the course of the Ascidian 

 development at a geological period anterior to the 

 present epoch. 



This being the case, it must be admitted that it is 

 quite possible — I do not say more than possible — that 

 other groups of animals besides parasites, Barnacles, 

 and Ascidians, are degenerate. It is quite possible 

 that animals with considerable complexity of structure, 

 at least as complex as the Ascidians, may have been 

 produced by degeneration from still more highly 

 organised ancestors. Any group of animals to which 

 we can turn may possibly be the result of degeneration, 

 and yet offer no evidence of that degeneration in its 

 growth from the egg. 



Accordingly, wherever we can note that a group 

 of organisms is characterised by habits likely to lead 

 to degeneration, such as I have enumerated, viz. 

 parasitism or immobility, or certain special modes of 



