THE CELL. 11 



of nuclein, while the protoplasm of the cell is constructed from other 

 albuminous bodies. 



Protoplasm is composed principally, then, of simple proteids and 

 compound proteids that lack phosphorus. Our most common and 

 typical type of an albuminous substance, or proteid, is the white of 

 an egg. This contains 12 per cent, of actual proteid substance, the 

 remainder being chiefly water. The albumins are the only bodies 

 that can safely be said to be found in all cells. Although the albu- 

 mins contain only five elements, C, H, N, S, and 0, yet the num- 

 ber of their atoms often exceeds a thousand. 



3. Various Other Substances occur in smaller proportions as car- 

 bohydrates; as glycogen in protoplasm of liver-cells; fats, seen in 

 protoplasm as fats or oil-drops ; and simpler substances which are the 

 result of decomposition of the proteids, or are concerned in its for- 

 mation; and also, inorganic salts, such as phosphates, and chlorides 

 of calcium, sodium, and potassium. 



NUCLEUS. 



From an examination of the protoplasm, we pass on to the 

 nucleus. As we have said before, "a cell is a mass of protoplasm con- 

 taining a nucleus/' Various properties and functions of an import- 

 ant nature have been assigned to protoplasm, but it is found that the 

 nucleus is equally as important. The classical experiments of the 

 old observers upon protoplasm led them to believe that the protoplasm 

 was the embodiment of all the functions of life. To them the nucleus 

 was unessential as regards the activities of life. The ruling power 

 of the protoplasm was dismissed when it was found that the nucleus 

 in reproduction of cells by division or impregnation underwent extra- 

 ordinary changes, while the protoplasm remained passive and quiet. 

 Within recent years there has set in a reaction, and the happy mean 

 'twixt the two extremes is now held to be correct: the two are of 

 equal importance. 



By extended research and with staining reagents such as carmin, 

 ha3matoxylin, etc., a distinct nucleus was found imbedded in the pro- 

 toplasm of most animal cells. For a long time, and until the micro- 

 scope was greatly improved, two classes of organisms appeared to be 

 the exceptions. They were, monera, the lowest and simplest, organ- 

 isms, and bacteria. Gradually the number of each class was reduced 

 until at the present day it may safely be said that every cell contains 

 a distinct nucleus. Every cell may thus be said to be characterized 

 by two general cell-constituents, protoplasm, and at least one nucleus. 



