Even if a drop of blood is drawn by pricking one's finger, and 

 carefully viewed with proper precaut'ons and under a sufficiently 

 high microscopic power, there will be seen among the innumerable 

 multitude of little circular disroidal bodies or corpuscles which 

 float in it and give it its color, a comparatively small number of 

 colorless corpuscles, of somewhat larger size and somewhat irregu- 

 lar shape. If this drop of blood be kept at the temperature of the 

 b:)dy, they will be seen to exhibit a marvellous activity, changing 

 their forms with the greatest rapidity, drawing in and thrusting 

 out prolongations of their substance, and creeping about as if they 

 were independent organisms. This substance which is so active is 

 simply a mass of protoplasm, and its activity differs in detail, 

 rather than in principle, from that of protoplasm of plant life. 

 The simplest form of life, as it emerges from the inorganic 

 to the organic world, consists of protoplasm. In the earliest 

 state of the human organism, in that in which it has just 

 become distinguishable from the egg in which it arises, it is 

 nothing but an aggregation of corpuscles or cells, and every 

 organ of the body was once no more than such an aggrega- 

 tion. Thus a nucleated mass of protoplasm turns out to be what 

 may be termed the structural unit of the human body, and in its 

 most perfect state it is a multiple of such units variously modified 

 and differentiated. Let us look at this little cell, ■'estled in a con- 

 genial environment. It is alive, it move>^, it comi-„ in contact with 

 small particles of inorganic matter ; it shapes itself so as to sur- 

 round them, and the little particles are absorbed into its organism 

 and they become a part of the living ce)' That function of the cell 

 which enables it to absorb the latent forces of the inorganic matter 

 unto itself, we call nutrition. If we watch it still further, we shall 

 see that it increases in size, it grows. But this little cell we have 

 been studying has yet a still brighter future : it has a latent force 

 within that has thus far been unobserved. Growth is the balance of 

 repair over waste, and when through assimilation of food into its sub- 

 stance, this cell reaches a certain size, the force of cohesion is over- 

 come by the release of the energy derived from food, and the cell 

 •divides equally at the kernel or nucleus, the soft slimy protoplasm 

 distributes itself around each nucleus as the two part companj', to 

 grow and divide again in like manner ad infinitum. You here 

 see the function of perpetual existence has been added — the func- 

 tion of self-preservation, by making two living things out of 

 one : the origin of parent and offspring, the beginning of repro- 

 duction. 



The fundamental principles of life were embraced in these four 

 functions: nutrition, growth, motion and reproduction. The living 

 cell being completed, it has since been allowed to work out its own 

 destiny. It began to unfold the mysterious possibilities that were 

 concealed within its little structure, and the unnumbered ages have 

 witnessed a mighty growth and development — a wonderful evolu- 

 tion of life. 



