SIMPLER PLANTS AND ANIMALS 



base of the branches, the pear-shaped ovary with its single 

 egg, and the male organ or spermary beside it looking like a 

 brilliantly colored, microscopic orange. In it are thousands 

 of sperm cells which finally break forth and make their way 

 to the egg. A short time after the egg is fertilized it falls from 

 the branch and later germinates into a new plant. 



Chara plants have a marshy odor often distinctly sulphiiry 

 and feel harsh and brittle to one's fingers. There are many 

 species, but in our flora Chara fragilis (Fig. 46) is the common 

 one. 



The limy covering of Chara stems makes them poor eating 

 and is an effective barrier to all sorts of herbivorous nibblers, 

 but vast numbers of diatoms and desmids settle on them and 

 these provide food for a large population of vegetarians. 



Occurrence: Cosmopolitan. July-August. 



Nitella. — Nitella (Fig. 47) is more delicate than Chara but is 

 so similar that it is often called by the same common name, 

 candelabra plant. Its branches grow out from the stem in 

 whorls like Chara, but both these and the intemodes are naked, 

 not covered by cells and seldom encrusted with lime as in 

 Chara. This gives them a translucent delicacy and easily dis- 

 tinguishes Nitella from its relative. 



Occurrence: Nitella is cosmopolitan, but less common than 

 Chara. July-August. 



Protozoans 



A protozoan is a minute animal, living as a solitary cell, 

 or in groups, when they are known as colonial protozoans. All 

 of them are microscopic or~nearly so (Fig. i , B) ; the typical 

 protozoans do not collect in large masses like the algas, but a 

 few of them are large enough to be seen with a hand-lens. 



Protozoans exist in untold numbers in both salt and fresh 

 waters and every pool and brook has its population of them. 

 A few of them are figured here. These are commonly found on 



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