280 Proceedings of the Royal Physical Society, 



cropped up before the mind's eye. Among these may he 

 mentioned the favourite subject of stock-taking of recent 

 work done in one or other of the departments of science in 

 which you are engaged. But the limitation of my special 

 knowledge in most of them precluded me from entertaining 

 any project of this kind. A man who cannot swim should 

 never go beyond his depth. I find it, therefore, more 

 prudent to restrict myself to a mere academic performance, 

 leaving to more competent men, such as our President and 

 Secretary, the duty of garnering the fruits of your own 

 labours as discoverers and investigators. In laying before 

 you a few stray thoughts on the theory of Organic Evolution, 

 more especially in its bearing on the human race, I claim 

 your indulgence if in some instances I utilise facts which 

 are known to me only through the researches of others. 



That all the higher animals which form so conspicuous a 

 portion of the organic world around us are genetically con- 

 nected by descent from common ancestors, may now be 

 accepted as a settled dogma in biology. The evidence, 

 however, on which this important generalisation is founded, 

 scarcely admits of experimental proof, because these 

 ancestors are no longer in life, owing to the inexorable 

 law which assigns to every individual organism, after a 

 more or less limited period of existence, a return into the 

 bosom of mother-earth. Indeed, of the vast majority, no 

 traces are now to be found, and the only means we have of 

 procuring any information of their former existence and 

 characteristics is by a laborious investigation of casts or 

 impressions of the bodies of some specimens which, by a 

 combination of fortuitous circumstances, have become 

 stereotyped in the crust of the globe. Such fossil 

 remains, however, disclose little more than the outlines 

 and fragmentary skeletons of these by-gone creatures, but 

 yet, in the hands of skilled palaeontologists, they have been 

 made to throw a flood of light on the dogma now under con- 

 sideration. To fully understand the doctrine of evolution, 

 one has, therefore, not only to examine living fauna as 

 regards the resemblances, differences, physical environments, 

 and geographical distribution of the different species, but 



