PLEUROCOCCUS VIRIDIS. 19 



The essential part of the cell is the protoplasm, a color- 

 less semi-fluid substance, which in this instance is obscured 

 by the green chlorophyll. It is the only really living 

 active agent in this as well as in all other plants. Its 

 presence here is made manifest by the yellowish-brown 

 color given by iodin. 



The nucleus is a special organ of the protoplasm to be 

 seen in most plant cells. It is definitely related to the 

 life of the cell, and is an important agent in the process 

 of forming new cells. 1 Chloroplasts are protoplasmic 

 bodies that hold the green pigment chlorophyll. The 

 protoplasm by the aid of the chlorophyll is able to pro- 

 duce, from the simple inorganic substances carbon dioxid 

 and water, certain complex foods such as starches and 

 sugars, a function wanting in all animals, and also want- 

 ing in many plants, e.g. Fungi and certain colorless 

 parasites that are not Fungi. 



The solid, firm, and nearly colorless cell-wall, consist- 

 ing essentially of cellulose, is a product of the protoplasm, 

 and serves as a protection to it. The fine granules seen 

 in the protoplasm are largely food materials produced by 

 the cell. 



The multiplication of the plant by cell-division is a 

 very common method throughout the vegetable kingdom. 

 The nucleus first divides, thus forming two new nuclei. 2 

 The proptolasm then divides, a nucleus remaining in 

 each part, and a wall is formed between. The two cells 

 thus produced soon attain the size of the original cell, 



1 These structures are not always made clear by iodin. Chloriodid 

 of zinc serves well to demonstrate them. 



2 Read on "nuclear divisions" in reference texts. 



