318 HAND-BOOK OF PHYSIOLOGY. 



there is capability of living. Hence the explanation of the difference 

 between the effect of appliance of external force in the two cases. Take, 

 for examples, the fertile but not yet living egg, and the barren or dead 

 one. Every application of force to the one must excite movement in the 

 direction of development; the force, if used at all, is transformed by the 

 germ into vital energy, or the power by which it can gather up and elab- 

 orate the materials for nutrition by which it is surrounded. Hence its 

 freedom throughout the brooding time from putrefaction. In the other 

 instance, the appliance of force excites only degeneration; if transformed 

 at all, it is only into chemical force, whereby the progress of destruction 

 is hastened; hence it soon rots. To the one, heat is the signal for devel- 

 opment, to the other for decay. By one it is taken up and manifested 

 anew, and in a higher form; to the other it gives the impetus for a still 

 quicker fall. 



Life, then, does not stand alone. It is but a special manifestation of 

 transformed force. * 'But if this be so/' it maybe said "if the resem- 

 blance of life to other forces be great, are not the differences still greater?" 



At the first glance, the distinctions between living organized tissue 

 and inorganic matter seem so great that the difficulty is in finding a like- 

 ness. And there is no doubt that these wide differences in both outward 

 configuration and intimate composition have been mainly the causes of 

 the delay in the recognition of the claims of life to a place among other 

 forces. And reasonably enough. For the notion that a plant or an ani- 

 mal can have any kind of relationship in the discharge of its functions to 

 a galvanic battery or a steam engine is sufficiently startling to the most 

 credulous. But so it has been proved to be. 



Among the distinctions between living and unorganized matter, that 

 which includes differences in structure and proximate chemical composi- 

 tion has been always reckoned a great one. The very terms organic and 

 inorganic were, until quite recently, almost synonymous with those which 

 implied the influence of life and the want of it. The science of chem- 

 istry, however, is a great leveller of artificial distinctions, and many com- 

 plex substances which, it was supposed, could not be formed without the 

 agency of life, can be now made directly from their elements or from very 

 simple combinations of these. The number of complex substances so 

 formed artificially is constantly increasing; and there seems to be no rea- 

 son for doubting that even such as albumin, gelatin, and the like, will be 

 ultimately produced without the intermediation of living structure. 



The formation of the latter, such an organized structure for instance 

 as a cell or a muscular fibre, is a different thing altogether. There is at 

 present no reason for believing that such will ever be formed by artificial 

 means; and, therefore, among the peculiarities of living force-transform- 

 ing agents, must be reckoned as a great and essential one, a special in- 

 timate structure, apart from mere ultimate or proximate chemical com- 



