Guilliermond - Atkinson 



Cytoplasm 



an enormous single vacuole which occupies the greater part of the 

 cell, forcing the nucleus to the periphery. This vacuole is often 

 traversed by thin cytoplasmic trabeculae which radiate from the 

 nucleus to join the parietal cytoplasm. 



Lipide granules are encountered in almost all, if not in all, 

 cells. They are scattered in the cytoplasm in more or less consid- 

 erable numbers according to the cells and their stage in develop- 

 ment. One also finds, moreover, various inclusions in the cyto- 

 plasm: reserve or by-products formed during cellular activity 

 (starch grains, crystalline proteins, various crystals, etc.) which 

 are localized either in the cytoplasm itself or in the plastids or in 

 the vacuoles. All these substances, however, are only transitory 

 products formed during cytoplasmic activity. 



The paraplasm:- We now turn to a new consideration. It has 



just been seen that in the cytoplasm 

 there are in suspension some elements 

 which are always present such as plas- 

 tids, chondriosomes, vacuoles and lipide 

 granules. Among these elements, a 

 distinction must be made between those 

 wiiich can be considered as belonging to 

 the living substance, to the architecture 

 of the cell, and those which simply re- 

 sult from its activity. Among the lat- 

 ter whose chemical composition is more 

 simple, there are some, like the starch 

 grains, which form in the plastids, 

 others, like many crystals, which are lo- 

 calized in the vacuoles, others still, like 

 the crystalline proteins, which are con- 

 tained in the cytoplasm itself. Now, the 

 cytoplasm is a substance which continues to exist permanently. It 

 presents a chemical composition still not well known but which 

 does not vary appreciably. It is a living substance. The plastids 

 are elements which are never formed de novo but, like the nucleus, 

 are transmitted by division from cell to cell. They, therefore, may 

 also be considered as living substance. The chondriosomes seem to 

 be of like nature. Such is not the case for the vacuoles. Although 

 always present in the cells, they appear to arise de novo and to dis- 

 appear only to be replaced by new ones. Furthermore, they enclose 

 substances which, all of them, are products of cytoplasmic activity : 

 reserve products, or waste products, or transitory products of 

 metabolism. They do not, therefore, seem to belong to the living 

 substances of the cell. This is true for the lipide granules 

 which are present in almost all cells, but which vary greatly in 

 quantity depending on the state of development of the cells : there 

 are cells which contain only a few, others in which the granules 

 accumulate in great quantity and fuse to form large globules filling 

 up the cytoplasm. These are also products of metabolism. Co- 

 existent with these visible products, there are others, like glycogen, 



Fig. 1. — Diagram of a plant 

 cell. C, chondriosome. Gg, lipide 

 granules. N, nucleus. P, chloro- 

 plasts. V, vacuole. 



