vegetables are evolved from ancestors wliich very closely resemble 

 them, and, until quite recently, it was believed that each creature 

 or plant was created by special fiat, and placed on those parts of 

 the earth which are best adapted for it. Mr. Weir proposed to 

 limit his arguments by drawing illustrations from the animal 

 kingdom — chiefly from the vertebrata, or creatures possessing a 

 backbone. 



If the Doctrine of Evolution is to be accepted, it must be 

 shown to be supported by evidence gathered, — 



1. From Development from the Ovum — Embryology. 



2. From Similarity in Structure — Morphology. 



3. From Distribution in Time — Palaeontology. 



4. From Distribution in Space — Zoogeography. 

 Embryology. — As far as the higher animals are concerned, 



all life proceeds from the egg ; and Von Baer pointed out that 

 during the egg state of existence, while gro^vth is going on, the 

 development of differences is also going on; and that these 

 differences become of greater and greater importance until birth 

 takes place. Thus the embryo of a dog, of whatever variety, 

 would, up to a certain stage, resemble other embryos of the same 

 species — a buU-dog for example, would resemble a greyhound ; at 

 birth a difference would be very apparent ; and at a month old the" 

 difference would be greater still. 



Birds are more closely allied to reptiles than is usually 

 believed, and Anatomists have found rudiments of teeth of 

 reptilian character in some imhatched birds. This fact has 

 recently been invested with deep interest, by the discovery of 

 fossil birds in America with teeth in the jaws. Again, in efts, 

 toads, and frogs, the embryonic form is that of a fish, and in the 

 tadpole state they are still true fishes, living in the water and 

 breathing by means of gills ; but when their lungs are developed 

 they leave the water, and breathe air like reptiles and the higher 

 vertebrata. 



The subject of Embryology is a vast one, nevertheless, all 

 the arguments that can be drawn from it appear to be in favour 

 of Evolution. Professor AUen Thomson, when President of the 

 British Association for the Advancement of Science, in referring 



