72 



BIOLOGICAL LECTURES. 



them requires nothing beyond the factors I have already named, 

 and there is no need of assuming anything more mysterious 

 than these. If all phenomena in the realm of the so-called 

 inoreanic natute be due to matter and its various motions, — and 

 of this there seems to be little reason to doubt, and no one 

 argues otherwise, — then what is the use of talking about forces 

 of any kind, seeing they have no existence. How much differ- 

 ence this will presently make in one's conceptions any one 

 may discover by omitting the use of the word "force" from 

 his vocabulary for a day or two, whenever he discourses and at- 

 tempts an explanation of a phenomenon. It will be perceived 

 that the word is used generally as a pretentious substitute for 

 ignorance. 



Living things, both plants and animals, were thought for a 

 long time to be endowed with a quality radically different from 

 inanimate things. The processes of digestion, assimilation, 

 growth, and the like were believed to be dependent upon a 

 peculiar agency capable of dominating the ordinary chemical 

 activities which otherwise would destroy the organism. This 

 was called vital force. Organic chemistry was the name given 

 to the processes by which a host of complex compounds were 

 formed in living things, and vital force was credited with being 

 the agency in all of them. By and by a chemist succeeded in 

 producing in an artificial way a single one of these products, 

 and the announcement was a stunner to both physiologists and 

 chemists. Soon other chemists found artificial ways of making 

 others, and to-day so great a number have been produced in 

 the laboratory that chemists do not hesitate to express their 

 belief that every organic substance, even protoplasm, may thus 

 be formed, and that also in the animal body there is no such 

 agency at all as was called vital force. Physiologists trace 

 physiological phenomena without exception to the activities of 

 ordinary forms of energy known as physical and chemical, not 

 because chemists have been able to build up all compounds 

 known, but because among the tens of thousands which have 

 been thus formed there is nothing more required than what 

 can be provided in a test tube ; and also because it has been 

 fairly well proved that there is a direct and quantitative rela- 



