13 



And now, wliat is the ultimate fate, and what the origin, of the 

 matter of life ? Is_it, as some of the older naturalists supposed, 

 difluLised throughout the universe in molecules, Avhich are inde- 

 structible and unchangeable in themselves ; but, in endless trans- 

 migration, unite in innumerable permutations, into the diversified 

 forms of life we know ? Or, is the matter of life com^posed of ordi- 

 nary matter, differing from it only in the manner in which its 

 atoms are aggregated. Is it built up of ordinary matter, and 

 again resolved into ordinary matter Avhcn its work is done? 

 Modern science does not hesitate a moment between these alter- 

 natives. Physiology writes over the portals of life 



" Debemur morti nos nostraque," 



with a profounder meaning tlian the Koman poet attached to 

 that melancholy line. Under whatever disguise it takes refuge, 

 whether fungus or oak, worm or man, the living protoplasm not 

 only ultimately dies and is resolved into its mineral and lifeless 

 constituents, but is always dying, aiid, strange as the jDaradox 

 may sound, could not live unless it died. In the wonderful story 

 of the " Peau de Chagrin," the hero becomes possessed of a magi- 

 cal wild ass's skin, which yields him the means of gratifying all 

 liis wishes. But its surface represents the duration of the propri- 

 etors life ; and for everv satisfied desire the skin shrinls 



s m 



pro- 

 portion to the intensity of fruition, until at length life and the 

 last handbreadth of the "Peau de Chagrin," disappear with the 

 gratification of a last wish. Balzac's studies had led him over a 

 wide range of thought and speculation, and his shadowing forth 

 of physiological truth in this strange story may have been inten- 

 tional. At any rate, the matter of life is a veritable "Peau de 

 Cliagrin," and for every vital act it is somewhat the smaller. All 

 work implies waste, and the Avork of life results, directly or indi- 

 rectly, in the waste of protoplasm. Every vv^ord uttered by a 

 speaker costs liim some physical loss ; and, in the strictest sense, 

 he burns that others may have light — so much eloquence, so much 

 of his body resolved into carbonic acid, water and urea. It is 

 clear that this process of expenditure cannot go on forever. But, 

 happily, the protoplasmic ;:>eaz« de chagrin differs from Balzac's in 

 its capacity of being repaired, and brought back to its full size, 

 after every exertion. For example, this present lecture, what- 

 ever its intellectual worth to you, has a certain j^hysical value to 

 me, which is, conceivably, expressible by the number of grains 



