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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



cal combustion is a single phenomenon, acciden- 

 tal in a way, having no harmonious connections 

 in Nature out of itself. Vital combustion, on the 

 contrary, presupposes a correlated renovation, a 

 phenomenon of the highest importance. The de- 

 scription of its chief characteristics will complete 

 our subject. 



The movement of renovation or organic syn- 

 thesis presents two chief modes. Sometimes syn- 

 thesis composes nutritive principles by the assim- 

 ilation of surrounding substance, and sometimes 

 it forms the elements of the tissues from it imme- 

 diately. Thus we observe, alongside the forma- 

 tion of direct products of chemical synthesis, the 

 appearance of the phenomena of moultings, or his- 

 tologic reparations, sometimes continuous, some- 

 times periodic. The phenomena of renewal, res- 

 toration, reparation, displayed in the adult indi- 

 vidual, are of the same kind as the phenomena of 

 generation and evolution, by which the embryo 

 in the beginning, composes its organs and anatom- 

 ical elements. The living being, then, is distin- 

 guished by generation and nutrition at the same 

 time ; we must combine and mingle these two or- 

 ders of phenomena, and, instead of dividing them 

 into distinct categories, we treat them as a single 

 act, completely similar in essence and mechanism. 

 With this conception, it is entirely correct to say 

 that nutrition is only continuous generation. Or- 

 ganic synthesis, generation, regeneration, renova- 

 tion, and even cicatrization, are aspects of one and 

 the same phenomenon — various manifestations of 

 one and the same agent, the germ. 



The germ is chiefly and specially the agent 

 of organization and nutrition ; it attracts cosmic 

 matter about it, and organizes it to form the new 

 being. But the germ can only manifest its organ- 

 izing power by itself performing combustions — 

 organic destructions. For this reason it is, at the 

 beginning, inclosed in a cell — the cell of the egg 

 — and there surrounds itself with those elaborated 

 nutritive materials which take the name of the 

 vitellus. 



The egg-cell, thus composed of the germ and 

 the vitellus, unfolds the new organism by segmen- 

 tation, by an infinite self-division into a number- 

 less quantity of cells, each provided with a germ 

 of nutrition. This cellular germ, called the nu- 

 cleus of the cell, attracts around it and elaborates 

 those special nutritive materials designed for com- 

 bustion in action by each of the elements of our 

 tissues or organs. When natural or accidental 

 phenomena of renovation occur; when, for in- 

 stance, a nerve that is cut repairs itself, and re- 

 sumes its functions, in such a case, too, it is the 



cellular kernels that, like the primordial germ 

 they are derived from, divide and increase in num- 

 ber, to recompose new tissues in the adult, in ex- 

 act repetition of the processes followed by the 

 embryo in its growth. 



All these very various phenomena of renova- 

 tion and organic synthesis have the distinctive 

 mark, as we have said, of being in a manner in- 

 visible to outward view. From the stillness that 

 reigns in an egg in course of hatching, we could 

 have no suspicion of the activity which is at work 

 in it, and the importance of the phenomena that 

 are there taking place ; at its exit only the new 

 being will display to us, by its vital manifesta- 

 tions, the wonders of that slow and secret work. 



It is the same with all our functions ; each one 

 has, we may say, its period of organizing incuba- 

 tion. When a vital act shows itself outwardly, 

 the conditions of it had been for a long time gath- 

 ering in that deep and quiet elaboration that makes 

 ready the causes of all phenomena. It is impor- 

 tant not to leave these two phases of physiological 

 operation out of view. If it is desired to modify 

 vital actions, they must be attacked in their hid- 

 den unfolding; when the phenomenon comes to 

 light, it is too late. In this, as in everything else, 

 nothing comes by sudden chance ; events seem- 

 ingly most abrupt have had their secret causes. 

 The object of science is exactly to discover these 

 elementary causes, and gain the power of modify- 

 ing and thus controlling the final appearance of 

 phenomena. 



In fine, we shall perceive, with distinction, in 

 the living body, two great groups of inverse phe- 

 nomena : functional phenomena, or vital waste ; 

 organic phenomena, or vital concentration. Life 

 is kept up by two orders of acts wholly contrasted 

 in their nature : the combustion of disassimilation, 

 which uses up living matter in the acting organs ; 

 the synthesis of assimilation, which repairs the 

 tissues in the organs at rest. The agents em- 

 ployed in these two kinds of phenomena are not 

 less diverse. Yital combustion borrows from 

 without that common agent of combustions — oxy- 

 gen ; or, when that is not to be had, the ferments, 

 whose disassimilating action may interpose in the 

 inner parts of the organism not reaohed by the air. 

 Organizing synthesis, on the contrary, has a spe- 

 cial agent — the germ, properly so called, or the 

 kernels of cells, the secondary germs that emanate 

 from it, and are found scattered throughout all 

 the elementary parts of the living body. So, too, 

 the conditions of functional disassimilation and 

 those of organic assimilation are widely different. 

 The same agents of combustion that waste the 



