THE FUNCTIONING OF TROTOPLASM 49 



pends, in part at least, and perhaps wholly, on the elec- 

 trical charges of the dissolved salts and the protein mesh- 

 work. Cytoplasm is thus seen to be an organized and 

 complicated colloidal system in which powerful but im- 

 perfectly understood forces are at work at the boundaries 

 between the protein gel and the liquid oil and water 

 solutions. 



The Functioning of Protoplasm. — We may thus 

 conceive protoplasm to be made and maintained as a 

 self-operating mechanism in response to the affinities of 

 the proteins which assemble or arrange themselves with 

 water into colloidal systems, and by means of the actions 

 and interactions on the faces of these systems, where a 

 great part of the energy requirements of the living or- 

 ganism are developed and satisfied. The operating or 

 functioning of the system thus described constitutes liv- 

 ing, or life. Living protoplasm is, then, a structure in 

 which chemical processes go on in response to atomic and 

 molecular affinities, physical as well as chemical change 

 continually taking place, with the binding, release, and 

 application of powerful forces which act upon the par- 

 ticles of matter, holding them in place as parts of systems, 

 pushing them out or pulling them in. Thus the function- 

 ing of protoplasm, living, is continual change, physical 

 and chemical. 



The Growth of Protoplasm. — The growth of proto- 

 plasm is one of the functions of this self-operating mecha- 

 nism, and consists in increasing or adding to the colloidal 

 systems which constitute the living substance. Thus 

 both water and colloidal substance increase as pro- 

 toplasm grows. The proportions vary in different stages 

 of the process of growth, but the systems are continued 

 with their physico-chemical capacities and character. 



The Death of Protoplasm. — When change becomes 

 impossible, or when it becomes excessive, in those col- 

 loidal systems of water, proteins, etc., which constitute 

 living protoplasm, death ensues. Death may be pro- 



