84 THE CELL DOCTRINE. 



extending over a period of several years. In fact 

 some of the drawings in this volume, and others 

 vi'hich have "been published elsewhere, equally favor- 

 able to this view, were made long before any specific 

 theory had been arrived at." 



'The " cell" or " elementary -part" as Dr. Beale pre- 

 fers to call it, is composed of matter in two states, 

 matter which \s forming, and matter which is formed ; 

 matter which has the power of growing by produc- 

 ing matter like itself out of pabulum or food, and 

 matter which possesses no such power, but results 

 from the death of the forming matter. The former 

 is known as germinal or living matter, the latter as 

 formed matter. The former, in varying quantity in 

 diiferent cells, is central in its situation (see frontis- 

 piece. Fig. 17), and includes what, has been called by 

 others nucleus, cell contents, protoplasm, endoplast. 

 The latter, also present in different quantity in differ- 

 ent cells, is peripheral (frontispiece, Fig. 17), and in- 

 cludes what is known as cell-wall, periplast, inter- 

 cellular substance, and products ot secretion. 



In its structural characters, germinal matter is soft, 

 transparent, colorless, and as far as can be determined 

 by the highest powers, structureless, being visible 

 only through its difference in refracting power as 

 compared with the menstruum in which it floats, or 

 by the granular matter it may entangle ; and these 

 characters are the same at every period of its exist- 

 ence. In the simplest vegetables they may be studied, 

 in the thallus of the sugar fungus, among the lowest 

 animals, in the amoeba (frontispiece, Fig. 16), and in 

 higher animals in the mucus-, pus-, or white blood-cor- 



