TRAINING NEEDFUL FOR NATURALISTS. 343 



of natural selection — experience difficulties in arriving at a 

 rational understanding of them, which are similar to those 

 experienced by the xmcivilized tribes of nature when con- 

 templating the latest complicated productions of engineer- 

 ing. Savages who see a ship of the line, or a locomotive 

 engine for the first time, look upon these objects as the 

 productions of a supernatural being, and cannot understand 

 how a man, an organism like themselves, could have pro- 

 duced such an engine. Even the uneducated classes of our 

 own race cannot comprehend such an intricate apparatus 

 in its actual workings, nor can they understand its purely 

 mechanical nature. Most naturalists, however, as Darwin 

 very justly remarks, stand in much the same position in 

 regard to the forms of organisms as do savages to ships of 

 the line and to locomotive engines. A rational understand- 

 ing of the purely mechanical origin of organic forms can 

 only be acquired by a thorough and general training in 

 Biology, and by a special knowledge of comparative 

 anatomy and the history of development. 



Among the remaining objections to the Theory of Descent, 

 I shall here finally refer to and refute but one more, as in 

 the eyes of many unscientific men it seems to possess great 

 weight. How are we, from the Theory of Descent, to conceive 

 of the origin of the mental faculties of animals, and more 

 especially their specific expressions — the so-called instincts ? 

 This difficult subject has been so minutely discussed by 

 Darwin in a special chapter of his chief work (the seventh), 

 that I must refer the reader to it. We must regard instincts 

 as essentially the habits of the soul acquired by adaptation, 

 and transmitted and fixed by inheritance through many 

 generations. Instincts are, therefore, like aU other habits, 



