The Idea of Evolution. 261 



the species were developed little by little and line by line. 

 They found some plants quite distinct, recognisable everywhere. 

 Others again could only be recognised by a good botanist ; and 

 then there were plants like the hawk-weeds, the brambles, and 

 the roses that could only be recognised by one or, at the utmost, 

 three people living, and those three people, from his own 

 personal experience, very frequently gave quite different names 

 to the specimen in question. Occasionally he had known cases 

 in which specimens of the same bramble from the same bush 

 Avere named differently by the same specialist in two succeeding 

 years. All that led to the view that the formation of species 

 had been in this gradual slow and cumulative manner. So far 

 he had given them the average general doctrine on that question. 

 The next stage was predestination — a very good old Scottish 

 expression, and which was the only one he could think of to 

 account for a good many facts that were otherwise inexplicable. 

 If they took the development of the plant, the gradual building 

 up of its complex body from the simple egg cell, they would see 

 that every step from the egg cell upwards followed directly 

 upon the previous step. They could not really imagine any 

 change in the regular sequence of development unless there was 

 a change in the circumstances or environment. It seemed 

 that the truth was very much of the same nature as the truth 

 of Newton's first law of motion — that an object would persist 

 in its state of rest or uniform motion in a straight line so long 

 as it was not induced by circumstances to change that motion. 

 He thought the development of the plant was of the same 

 ordinary continuous manner. Each step depended upon the 

 previous one, and unless environment altered it, the sequence 

 would be the same and lead to the same result. But not merely 

 so, any change in the conditions and the surroundings, however 

 slight, would affect that development and alter that develop- 

 ment. Thus by these slow changes in the environment — most 

 of which were utterly beyond the power of any instrument devised 

 by mankind to record — we had a differentiation which had pro- 

 duced a complex mixture of characters which we called a 

 species or plant. He would go so far as to say from his own 

 experience of botany and plant life generally, that one found 

 a very curious and a verj' striking resemblance between the 

 laws concerning the individual — a single plant or animal bodj- — 



