320 PROGRESS OF SCIENCE IN THE CENTURY. 



matter is neither permanent nor quiescent, but is in 

 more or less constant internal motion.'' In some- 

 what similar terms, Prof. Gaskell expounds the idea 

 that life implies an alternation of two processes — one 

 of them a running down or disruption (katabolism), 

 the other a winding up or construction (anabolism). 



THE UNSOLVED SECRET OF THE ORGANISM. 



In the preceding portion of this chapter we have 

 suggested the nature of the analysis by which the in- 

 tact living creature has been, so to speak, taken to 

 pieces, as one might do with a watch, and then theo- 

 retically reconstructed. Organism, organs, tissues, 

 cells, protoplasm — these words express the various 

 levels of analysis, and one result at least has been 

 a greater precision of description, a more detailed 

 and vivid picture of the facts of the case. 



As the analysis has proceeded throughout the cen- 

 tury, the enthusiasm of discovery has led again and 

 again to a short-lived belief that a solution of the 

 secret of the organism had been reached, — now as a 

 system of correlated organs, or again as a city of 

 co-operating cells. The discovery of the mainspring 

 may be said to disclose the secret of the watch, and 

 the discovery of the cylinder and piston may be said 

 to disclose the secret of the steam-engine; and so it 

 has seemed to some that the secret of the organism 

 has been discovered in the combined functioning 

 of the organs, in the combined properties of the 

 tissues, in the combined changes of the cells, or 

 in the metabolism of the protoplasm. But just as 

 the mainspring's elasticity demands further analysis, 

 and just as the change of water into expansive 

 steam does not quite explain itself, so the biologists 

 have sooner or later come to see that their presumed 



