FUNDAMENTAL INTERNAL STRUCTURE OF PLANT BODY 9 



cells — involves definite nuclear changes, which has led to 

 the opinion that hereditary characteristics are carried by 

 nuclear matter. The structure of the nucleus is indeed 

 complex, and there is a wonderful chain of changes that 

 it goes through at the time of cell division. 



Protoplasm. — In 1840, Hugo von Mohl drew attention to 

 the fact that the slimy substance in the plant cell was 

 responsible for its life, and that as soon as it was removed, 

 the cell no longer had the properties of livingness. The 

 name protoplasm was applied to the living portion of the 

 plant cell. Somewhat later, 1850, Ferdinand Cohn, gave 

 positive evidence of the identity of the living material 

 (protoplasm) in plant cells, and of the living material (so- 

 called "sarcode") in animal cells. 



If we examine a small bit of protoplasm under the micro- 

 scope we see that it is a semi-transparent, jelly-Uke, rather 

 granular substance, resembling very much the white of an 

 egg. It feels slimy. 



Protoplasm is a very complex chemical substance. Al- 

 though no element has ever been found in protoplasm that 

 is not also found in the common substances in the world 

 about us, the exact arrangement and proportions of these 

 elements has not been ascertained, except in a general way. 

 It is quite clearly established that protoplasm is a proteid, 

 of complex nature, with water as a solvent. Proteids form 

 about one-half or two-thirds of the dry substance of pro- 

 toplasm. The remainder is fat, sugar, and other carbohy- 

 drates, organic acids, organic bases, and some mineral 

 substances. 



