Cleland • Cytology: the Study of the Cell 



111 



Ralph E. Cleland 



Cytology: the Study of the Cell 



Reprinted with the permission of the author 

 and pubhsher from American Journal of 

 Botany 43(10) :870-881, 1956. 



In their efforts to learn about life 

 and living beings, biologists have de- 

 veloped many specialties, for although 

 they know but a tiny fraction of what 

 they need to know in order to under- 

 stand fully what Hfe is and how it 

 functions, the sum total of biological 

 knowledge is already far too extensive 

 and complex for any one man to grasp 

 it all. And so, some biologists have 

 concerned themselves primarily with 

 the identification and recognition of 

 the different kinds of organisms, others 

 with the manifold structures which 

 these organisms have developed; still 

 others have sought to analyze their ac- 

 tivities, how they nourish themselves, 

 grow and reproduce, how they behave 

 in their native surroundings, and under 

 controlled conditions. 



Most of these and other specialties, 

 however, attack the problem of the na- 

 ture of life only indirectly, by studying 

 the varied manifestations of life, the 

 results of life activity. It is only by a 

 study of that part of a living organism 

 which is itself alive (the so-called pro- 

 toplasm ) that one can hope to gain an 

 understanding of what hfe is in essence, 

 what lies at the bottom of and is re- 



sponsible for the phenomena which to- 

 gether make up what we call life. To 

 achieve this goal, one must turn to the 

 cell, for protoplasm exists, with very 

 few exceptions, not in large masses, but 

 in minute units which are called cells. 

 Cytology is the study of the cell, and it 

 is, therefore, of all fields the one which 

 comes closest to the heart of the major 

 quest of biology'— the understanding of 

 life in its essence. 



The cell is a marvelous microcosm, 

 extremely small, yet unbelie\ably com- 

 plex. Although protoplasm is incom- 

 parably the most complex system 

 known, it is organized into units whose 

 size, or lack of size, is difficult for the 

 average man to grasp. As the late Pro- 

 fessor Sponsler has pointed out. the 

 average-sized cell has a volume about 

 one-millionth that of the average rain- 

 drop. It might seem that a unit of mat- 

 ter so small would be incapable of 

 containing a substance as complicated 

 as protoplasm. The complexities of 

 protoplasm, however, are at the molec- 

 ular level. It is an organized system of 

 molecules of myriad kinds, some sim- 

 ple, some ranging up to the most com- 

 plex molecules known, each kind of 



