A SCIENTIFIC EXPLANATION OF LIFE 81 



iarity with the striking peculiarities of these substances is such that we 

 pass with the greatest readiness from one to the other, and treat them 

 all in essentially suitable ways. 



What do we know about things that are fit in an ever-changing 

 environment ? In the first place they are things which have had a long 

 history, and though we are still wofully ignorant of the conditions 

 under which this history has been worked out, we do feel reasonably 

 certain that all life is of a common stock, and that we have as good 

 reasons for speaking of the brotherhood of living things as we have for 

 speaking of the brotherhood of men. We know with much greater de- 

 tail that fit things assimilate food, that they excrete wastes and that 

 they secrete substances useful to themselves. We know too that they 

 grow, repair wounds, and often restore very complex lost parts ; that by 

 a marvelous process of development they reproduce their kind from 

 spores, gemmules, buds and eggs; and finally, we suspect that many of 

 them have minds in some way like our own. We know with certainty 

 that we ourselves have sensations, feelings, emotions, knowledge and 

 the power to communicate much of all this to others. Strangest of 

 all, we have a fairly complete equipment of self-knowledge, and we 

 spend much of our time in thinking and talking about our origin and 

 our destinv. 



The anatomist tells us that things which do all this are composed 

 of many complicated parts visible to the naked eye; the histologist 

 analyzes these parts or tissues microscopically, and finds that they are 

 made up of unit masses, the cells, or of the products of cells. From 

 the embryologist we learn in detail how each of the myriad cells of the 

 body comes from preexisting ones, and how by tracing development 

 back to its earliest stages, we finally reach the egg. Cytology carries the 

 dismemberment a step farther by discovering, classifying and naming, 

 not only the minuter parts of the cell, but its very granules. Biological 

 chemistry tells us what substances are found in the protoplasm; chem- 

 istry what elements are present and their proportion ; physics that these 

 elements are molecular in structure, that each molecule is made up of 

 smaller units, the atoms, and finally, the newest physics of all dissects 

 the atoms and promises to show that these, instead of being simple, are 

 in reality constellations of electrons. When we consider that a single 

 protein molecule may contain perhaps 2,304 atoms, more or less, that 

 the number of protein molecules in a cell is unknown, that there are 

 millions of cells to the man, we realize that our bodies are fearfully 

 and wonderfully made, and that if our ears were sensitized to only a 

 fraction of the rush and bustle within each protein molecule we should 

 be deafened as with the roar of a Bessemer furnace. 



This analysis is far from complete, but thousands of men through- 

 out the world are contributing, each the small share which he can, 



VOL. LXXXI. — 6. 



