VERTEBRATE DESCENT 85 



segmental nerves. . . . Not only, then, are the 

 nerve-masses in the two systems [appendiculate 

 and vertebrate] exactly comparable, but in the 

 very place where the oesophageal tube is found 

 in the invertebrate, the infundibular tube exists 

 in the vertebrate. ..." All this is true, but 

 what Dr Gaskell does not relate at this crucial 

 point of his narrative (I.e., p. 14) is that the 

 infundibulum also occurs essentially at the same 

 horizon, with reference to the segmental nerves, 

 as the anterior neuropore and olfactory pit of 

 Amphioxus, 1 where there are likewise two 

 anterior pairs of sensory cranial nerves ter- 

 minating in peripheral ganglion cells on the 

 prseoral lobe. 



It is not particularly edifying to pursue one 

 phantom rather than another ; and the spirit of 

 morphology may be said to reside not so much 

 in a desire for ultimate truth, that is to say, to 

 attain the unattainable, as in the will to accept 

 nothing but the truth. Applying this aphorism 

 to the special case of the two opposing theories 

 of vertebrate descent, namely, the Appendiculate 

 theory and the Protochordate theory, we may 

 say that if the latter fails to satisfy, so at least 

 does the former. It is necessary to codify the 

 facts ; but this can be done for the present upon 

 a broad basis of convergence better than by 

 an unrestrained use of homology. 



1 Dr Gaskell's references to the anterior neuropore of Amphioxus 

 occur on pp. 220 and 457 of his work, to which I refer the reader. 



F 2 



