170 BOTANY. 



302. Fertilization is doubtless effected by these antliero- 

 zoids coming in contact with the protoplasm of the carpo- 

 gone, but the actual entrance of the former has not yet 

 been seen. After fertilization the protoplasm in the car- 

 pogone increases considerably in size, and forms a cellulose 

 coat of its own. The cells which support the carpogone 

 send out lateral branches, which grow up and closely sur- 

 round it, finally covering it entirely (excepting the tricho- 

 gyne) with a cellular thick- walled " pericarp " {B, r). The 

 whole mass, including the fertilized carpogone and its in- 

 vesting pericarp, . constitutes the simplest form of spore- 

 fruit (the sporocarp). 



303. The further growth of the spore-fruit takes place 

 the next spring by the swelling of the protoplasmic con- 

 tents, and the consequent rupture of the pericarp ; the 

 inner portion divides into several cells, G (the proper fruit- 

 spores), which give rise to zoospores closely resembling 

 those developed from the vegetative cells. Prom each 

 zoospore a new plant eventually arises. 



This class contains but twelve or thirteen species, falling within 

 the single order (10) Coleochsetacese. 



Practical Studies. — (a) These little plants occur in fresh-water 

 pools as little green masses adhering to leaves, sticks, the stems of 

 living plants, etc. According to Wolle, we have five species. 



(b) The sexual process and the development of the sexual organs 

 occur in May, June, and July. 



Systematic Literature. — Wolle, Fresh-water Algae of the United 

 States, 63-65. De Toni, Sylloge Algarum, 1 : 6-12. Flora of Ne- 

 braska, 2 : 119, 130. pi. S3. 



Class 5. RHODOPHYCE.a:. The Eed Seaweeds. 



304. The plants of this class, which are almost without 

 an exception marine, are among the most beautiful and in- 

 teresting members of the vegetable kingdom. All have 



