MODERN CONCEPTION OF PROTOPLASM. 27 



physical osmosis ; it is modified by the fact that the cells 

 are living. 



From the point of view of a student of physics Dr. J. Joly 

 draws the following contrast between an animate and an 

 inanimate body : — " While the transfer of energy into any 

 inanimate material system is attended by effects retardative 

 of the transfer and conducive to dissipation, the transfer of 

 energy into any animate material system is attended by 

 effects conducive to the transfer and retardative of dis- 

 sipation." 



But though we cannot analyse living matter, nor thoroughly 

 explain the changes by which the material of the body 

 breaks down or is built up, we can trace, by chemical 

 analysis, how food passes through various transformations 

 till it becomes a useable part of the living body, and we can 

 also catch some of the waste products formed when muscles 

 or other parts are active. 



Apart from any theory, it is certain that waste products 

 are formed when work is done, and that living animals have 

 a marvellous power of rapid repair, of ceaselessly changing, 

 and yet remaining more or less the same. Theory begins 

 when we attempt to make the general idea of waste and 

 repair more precise. In the study of "protoplasm," both 

 morphologist and physiologist have reached their strict 

 limits. Further analysis becomes physical and chemical, 

 and ends in the confession that protoplasm is a marvellous 

 form of matter in motion or a subtle kind of motion of 

 which we can form only a very vague conception. 



What is known in regard to tlie structure of protoplasm does not help 

 the physiologist very much. As we shall afterwards see, the micro- 

 scopists discover an intricate network which pervades each unit of living 

 matter, but no physiologist dreams of explaining the life of a cell in 

 terms of its microscopically visible structure. Vet, as Burdon Sander- 

 son says, "We still hold to the fundamental principle that living matter 

 acts by virtue of its structure, provided the term structure be used in a 

 sense which carries it beyond the limits of anatomical investigation, 

 i.e., beyond the knowledge which can be attained either by the scalpel 

 or the microscope." But, in the end, this means that living matter acts 

 in virtue of its peculiar qualities, its characteristic motion, of which we 

 can form only a hypothetical conception, and can give no scientific 

 explanation. 



One general idea, however, the study of structure has suggested, 

 which the conclusions of physiologists corroborate. This idea is — that 



