26 THE FOUNDATION Part I 



and a living ameba shifting its shape through the water on the same micro- 

 scopic slide can be seen to have many differences. Their differences are not 

 surprising, but that their respective protoplasm should look so much alike is 

 unforgettable. 



Protoplasm is a glassy fluid jelly that suggests the white of an egg be- 

 sprinkled with translucent particles and globules of liquid whose sizes and 

 arrangement change, at one time forming an open network, at another crowded 

 together (Fig. 2.11). Even through the microscope protoplasm often appears 

 inert. It is never really so as long as it is alive and after that it ceases to exist. 

 Dead protoplasm is only the somehow disorganized remains of protoplasm 

 and a contradiction of its name. 



Structure. Protoplasm consists of a watery solution (hyaloplasm) in which 

 salts and other substances are dissolved and in which solid and semisolid 

 bodies are suspended. Many of these are molecules, mainly proteins that are 

 invisible through ordinary microscopes; others are clearly visible droplets. 

 Water may pass into protoplasm, making it more liquid, or out of it leaving 

 it less so. Under osmotic pressure (Fig. 2.12) minute amounts of solution 

 pass in or out of the droplets by way of their surface films which play the 

 part of semipermeable membranes. The numbers and sizes of the suspended 

 bodies constitute a relatively enormous surface, all of it inviting to chemical 

 and physical changes (Fig. 3.1). 



Protoplasm is an exceedingly complex colloid. At one time it may be as 

 fluid as water (sol state) and at another a jelly (gel state) depending upon 



Fig. 3.1. In keeping with their colloidal nature, even minute particles in proto- 

 plasm present a relatively enormous surface to the molecules which continually 

 jostle them. (Courtesy, Gerard: Unresting Cells. New York, Harper & Bros., 

 1940.) 



