THE DISCOVERER 67 



and, whenever chance offered, compared, giving 

 special attention to the family of the Medusae, his 

 memoir on which laid the foundation-stone of his 

 scientific fame. It should be noted that that memoir 

 was written in 1848, eleven years before the publica- 

 tion of the Origin of Species, because in determining 

 the value of any scientific, and, especially, of biolog- 

 ical work, its chronological place must be taken into 

 account. In science the Old and the New Dispensa- 

 tion may be severally defined as the Pre-Darwinian 

 and the Post-Darwinian, and perhaps a brief survey 

 of what advance towards knowledge of the funda- 

 mental unity of living things had been reached during 

 the Old Dispensation may make clearer the bearing 

 of Huxley's discoveries, and explain why their signifi- 

 cance was not apparent even to himself. 



The great name of Aristotle is associated with the 

 earliest attempt at a classification of animals. This 

 was based, in the main, on likenesses of external 

 structure, and was accepted, without fundamental 

 variation, for the long period of eighteen hundred 

 years. The first step towards any important revision 

 was taken, in the seventeenth century, by Ray, 

 "the father of modern zoology." In the eighteenth 

 century Boerhaave's experiments proved that all liv- 

 ing things are built up of the same materials, while 

 Hunter demonstrated the likenesses in animal 



