24 PE0CBEDING8 OF THE 



The special message of Darwin to biology was the vindication of 

 function, and the demonstration that it was the use of parts and 

 not their shape which determined their significance, — that rela- 

 tionship between different types was a question of descent and of 

 survival, and therefore depended not on form but on fitness, that 

 is to say, on physiological function. It is curious to note, with this 

 relapse into scholiasticism, the old tendency to intolerance of new 

 ideas and of any light on the problems at issue other than that 

 shed by some enshrined man-made theory at the end of a dark 

 passage. In fact some members of the zoological hierarchy 

 apparently regard the attempt to throw light from any other 

 direction a? impious, and associate it, like many worthy divines 

 did the work of Darwin, with the Author of all evil. I would 

 not however like to suggest that Proiessor MacBride entertained 

 any such comminatory feelings or was conscious of any spirit of 

 religious intolerance when he speaks of the " diabolical ingenuity " 

 of Gaskell's theory. But surely the odium ihcologicum is out of 

 place in dealing with biological problems. A sacerdotal attitude 

 of mind will never advance our knowledge of natural phenomena 

 or of the origin of Vertebrates. It is a happy augury for the 

 revival of freedom of thousfht in English biology that the Linnean 

 Society should, in this jubilee year of Darwin, have devoted an 

 evening to the discussion of a theory, which, I believe, will prove 

 to be the most important contribution to the history of our race 

 since the publication of the ' Descent of Man.' 



Mr. E. S. GooDEicn, F.E.S., F.L.S., stated that before em- 

 barking on a theory as to the origin of the Vertebrates, we may 

 attempt to determine what must have been the structure of the 

 primitive early Vertebrate from which the Cephalochorda, Cyclo- 

 stomata, and Gnathostomata (Fish and higher Vertebrates) have 

 been derived. That all these forms are bilaterally symmetrical 

 ccelomate animals, provided with gill-slits, notochord, and dorsal 

 central nervous system, will be granted to start with ; but we 

 must further try to fiud out what has been the general course of 

 differentiation and specialization, to distiuguish the higher from 

 the lower forms, and to point out what other characters must 

 have been absent or present from the undifferentiated ancestral 

 stage common to them all. 



With considerable certainty Gnathostomes can be traced back 

 to an aquatic fish-like ancestor, in general structure not unlike 

 the modern Selachian. It possessed biting jaws with true teeth, 

 a general covering of denticles, open branchial slits, paired and 

 median fins, a cartilaginous endoskeleton, and well-developed 

 sense-organs. 



The Cyclostomes belong to an altogether lower grade of organi- 

 sation, the primitive characters of which cannot be merely due to 

 degeneration. The segmentation of the body is more complete, 

 and the segments are more uniform. This is especially the case 



