726 



SCIENCE. 



[N. S. Vol. VII. No. 178 



plied to organisms, but have only figura- 

 tive meaning when applied to any other of 

 the classes of matter or material bodies. 



When a living organism is compared with 

 a mechanical engine we note, first, that the 

 M'ork done by the machine is all accounted 

 for by (a) the amount of coal burned and 

 other potential energj'' entering in a sim- 

 ilar way ; and, second, that the construction 

 (what Maxwell called the ' configuration of 

 the mass ') of the machine is accounted 

 for by (6) the energj^ of the laborers 

 expended in building it, together with (e) 

 the potential energy of the bodies of matter 

 used in the construction. But after bal- 

 ancing all these resources with the corre- 

 sponding work accomplished, there still ap- 

 pears an item of cost of energy that has 

 gone into the machine which must be rep- 

 resented also on the side of work done, viz. : 

 (rf) the designing of the architect. 



Emploj'ing the same evidence which Tait 

 deemed to be valid as a proof of the objective 

 reality of energy, /. c, the price of labor, 

 we discover that the architect's labor must 

 be accounted for in the work done, or 

 else it was wasted energj\ Furthermore, 

 because, on the potential side of the 

 account, we are able to sharplj^ distinguish 

 the designing from the constructing of the 

 engine, we are authorized to reckon them 

 as separate elements in the cost of the work 

 done. It is to be noted that the particular 

 kind of work performed by the architect, 

 although it involves motion, is not strictlj' 

 speaking any particular mode of motion, 

 which may be measured in terms of horse- 

 power, though measurable in terms of man- 

 power. This may explain the reason why 

 no account of his work is taken in estimating 

 the potential energy of a machine. Never- 

 theless, all know that it requires the ex- 

 penditure of energy which has a price, and 

 is exerted onlj- hx a living organism. 



If designing costs energy in the con- 

 sti'uction of a physical machine, is it not 



reasonable to look for a similar expendi- 

 ture of energy in the construction of a 

 living machine? In the phenomena of an 

 organism we find the same groups of ex- 

 penditure involved in the work done. 

 These expenses are (a) the outside energy 

 of heat, etc., of the food consumed ; (i) the 

 energy used in tissues exhausted in growth 

 of construction ; (c) that of the materials 

 built into the structure with their potential 

 energies abiding with them. These three, 

 like the first three in machine construction, 

 are accounted for on both sides of the 

 equation. There remains to be considered 

 the fourth group (d), viz.: that which cor- 

 responds to the designing of the machine and 

 the potentiality of work consequent upon 

 the designing. It will now be evident that, 

 in the organism, that group of phenomena 

 classified above as genetic constitutes this 

 fourth group. The importance of, and the 

 direction in which successful search for the 

 'source of genetic energy is likely to be 

 made, are suggested by the following three 

 facts. First the chief aim of biological in- 

 vestigations for the last half century has 

 centered about the search for exactly this 

 determining cause of the particular form of 

 construction of organisms. This, in itself, 

 is suificient evidence of a prevailing belief 

 that some such cause is to be naturallj' ac- 

 counted for. Secondlj', the main points of 

 construction of a particular organism cor- 

 respond to those of the parent organism, and 

 not to anything in the material of which it 

 is constructed, is sufiicient to suggest the 

 direction from which the energ}' comes 

 which determines the construction. A 

 third fact, that the three kinds of genetic 

 phenomena (metabolism, development and 

 evolution) are but elaborations of a single 

 mode of operation, further points to the 

 probability that the determining energy in 

 question is the same for each. And all 

 these considerations seem to lead directly to 

 the conclusion, that some form of energy 



