6 CHEMICAL AFFINITY AND 



used in our schools and colleges, the animal frame is compared 

 to a watch with all its interdependent wheels and pulleys, which 

 can be put together after all the parts have been manufactured 

 separately. In our institutes of instruction we have very little 

 or nothing of the physiology of growth and development taught, 

 because the text-books are devoted to an enumeration of the 

 organs of the adult body ; and as the movements of the animal 

 frame are illustrated by mechanical contrivances, pulleys, levers, 

 and the like, the digestion by chemical forces, and the circula- 

 tion by mechanical propulsion, it is very natural that scholars 

 should grow up with the idea that the human frame is moulded 

 upon a mechanical contrivance. 



This is of what I would totally disabuse your minds. Al- 

 though there may be a certain degree of truth in it, yet it is in 

 such a small proportion to what is commonly received to be the 

 truth, that I would rather, for the present purposes, you had 

 never heard of such a thing as an organized being, for then 

 your minds would not be diverted, by any preconceived ideas, 

 from the argument which I am about to lay before you. I beg, 

 therefore, that you will allow me to lead you on, unrestrainedly, 

 step by step, in the new path which I have laid out for the pres- 

 ent occasion. 



In the preparation of these lectures I have revised the whole 

 history of the origin of life, and of the mode of development of 

 animals, as it is understood at the present day. 



I have commenced with the lowest and simplest forms of life ; 

 those obscure manifestations of a living existence, immediately 

 upon, or rather just this side of the confines of mere chemical 

 association. The characteristics of these I have carefully bal- 

 anced between the probabilities of life on the one hand, and of 

 mere existence without life on the other. 



This no doubt seems to you like a mystery ; and so it is, in a 

 measure at least ; and I would, certainly, rather that it might so 

 appear at the outset, than that it should be involved in your 

 minds with any of the mechanical ideas of which I have spoken, 

 when referring to Paley's work. 



