SOLENOCYTES 157 



strongly recommending the reader, if he has 

 not done so already, to refer to the original 

 volume, which is a very remarkable document 

 of research. 1 The citation will serve to illustrate 

 Dr Gaskell's point of view in this matter, and 

 I make no further comment upon it, relying 

 upon what has gone before except to point 

 out that it is not quite correct to say that the 

 Polychaeta as a whole are the highest forms of 

 Annelida. It is precisely among the Polychaeta 

 that the nervous system is often in contact 

 with the epidermis, and it is here that the 

 cerebral ganglion retains its primitive position 

 in the prostomium. 



This is what he says : " It is to me most 

 interesting to find that the very group of 

 Annelids, the Polychaeta, which possess soleno- 

 cytes so remarkably resembling those of the 

 excretory organs of Amphioxus, are the highest 

 and most developed of all the Annelida. I 

 have argued throughout that the law of evolu- 

 tion consists in the origination of successive 

 forms from the dominant group then alive, 

 dominance signifying the highest type of brain- 

 power achieved up to that time." The ways of 

 evolution are obscure and peculiar ; logically 

 one would think that they ought to keep 

 pace with the increase of brain-power ; naturally 



1 W. H. Gaskell, "The Origin of Vertebrates," London, 1908, 

 see p. 395. 



