FUNDAMENTALS OF STIU CTURE AND Fl NC'lioN 



V 



LIFE AND PROTOPLASM 



Preview. What is being alive? • Metabolism • Some signs of mani- 

 festation of life • The production and use of enzymes associated with living 

 things ■ Structure of protoplasm • Protoplasm and the cell • Chemical or- 

 ganization of living matter • Protoplasm a complex mixture • Protoplasm 

 a colloidal mixture • Diffusion ■ Osmosis and its significance to living cells • 

 Suggested readings. 



PREVIEW 



Being alive is something that we all know a little about. Liveliness 

 is associated with those of one group who are "up and coming," 

 those who are active, both mentall}^ and physically. If living things 

 are thought about a little more closely, certain things are attributed 

 to them : they move, feed, grow, are sensitive, and they reproduce their 

 kind. The scientist goes a step further and compares the living thing.s 

 with those which do not possess this mysterious something we call 

 life. He says life is a manifestation of forces, like a flame, or elec- 

 tricity. He goes beyond superficial observation and asks himself 

 a good many questions about the make-up and action of the living 

 things which fill his environment. Some of the problems with which 

 one is confronted are relatively simple and may be solved with a little 

 close observation, even without the aid of a microscope, but other 

 problems are speculative and may never be answered in full. 



If the problems were to be assembled with a view to attempting 

 their solution, some of the more important might be the following : 

 What is being alive? What differentiates living stuff from non- 

 living? What is known about the ultimate composition of the living 

 stuff ? Is it different for animals and for plants ? And what common 

 characteristics can be found for i)lants and animals? 



It is obvious that our problems resolve themselves into two gr()Ui)s. 

 those which are more or less speculative and those which depend on 

 the knowledge provided by the physicist, chemi.st, and biologist. 

 The newer knowledge of chemistry and physics and the u.se of the 

 refinements of the compound microscope have made possible mudi 

 that was undreamed of a i'o^^■ decades ago. It is only 260 years since 



12.') 



