1874 LETTER TO HAECKEL 15 1 



" Pfaffe." l There are " halb-Pfaffen " as weU as " halb- 

 Atfen." 2 So if what I say about " Anthropogenic " seems 

 very little to what I say about the Quarterly Review 

 do not be offended. It will all serve the good cause. 



I have been working very hard lately at the lower 

 vertebrata, and getting out results which will interest 

 you greatly. Your suggestion that Rathke's canals in 

 Amphioxus 5 are the Wolffian ducts was a capital shot, 

 but it just missed the mark because Rathke's canals do 

 not exist. Nevertheless there are two half canals, the 

 dorsal walls of which meet in the raphe described by 

 Stieda, and the plaited lining of this wall (a) is, I believe, 

 the renal organ. Moreover, I have found the skull and 

 brain of Amphioxus, both of which are very large (like a 

 vertebrate embryo's) instead of being rudimentary as we 

 all have thought, and exhibit the primitive segmentation 

 of the " Urwirbelthier " 4 skull 



Thus the skull of Petromyzon answers to about fourteen 

 segments of the body of Amphioxus, fused together and 

 indistinguishable in even the earliest embryonic state of 

 the higher vertebrata. 



Does this take your breath away ? Well, in due time 

 you shall be convinced. I sent in a brief notice to the 

 last meeting of the Royal Society, which will soon be in 

 your hands. 



I need not tell you of the importance of all this. It 

 is unlucky for Semper that he has just put Amphioxus 

 out of the Vertebrata altogether because it is demon- 

 strable that Amphioxus is nearer than could have been 

 hoped to the condition of the primitive vertebrate a far 

 more regular and respectable sort of ancestor than even 

 you suspected. For you see " Acrania " will have to go. 



I think we must have an English translation of the 

 Anthropogenic. There is great interest in these questions 



Parson. 2 Lit. half-apes ; the Prosimiee and Lemurs. 



3 The Lancelot. 4 Primitive vertebrate. 



