THE GREAT GROUPS OF ALG^ 



247 



spore is organized. As the gametes 

 look alike, the process is conjuga- 

 tion, and the sex spore is a zygote, 

 which, with its heavy wall, is rec- 

 ognized to be a resting sporo. At 

 the beginning of each growing 

 season, the well-protected zygotes 

 which have endured the winter 

 germinate directly into new S2)i- 

 7'Of/i/ra filaments. 



On account of this peculiar 

 style of sexual reproduction, in 

 which gametes are not discharged, 

 but reach each other through sjje- 

 cial tubes, Spirogyvd and its allies 

 are called Conjugate forms — that 

 is, forms whose bodies are "yoked 

 together " during the fusion of the 

 gametes. 



In some of the Conjugate forms 

 the zygote is formed in the connect- 

 ing tube (Fig. 215, ,1), and some- 

 times zygotes are formed without 

 conjugation (Fig. 215, i?). Among 

 the Conjugate forms the Desmids 

 are of great interest and beauty, 

 being one-celled, the cells being 

 organized into two distinct lialves 

 (Fig. 216). 



168. Conclusions. — The (Jreen 

 Algfe, as indicated by the illustra- 

 tions given above, include simple 

 one-celled forms which reproduce 

 by fission, but they are chiefly fila- 

 mentous forms, simple or branching. These filamentous 

 bodies either have the cells separated from one another 

 17 



. 215. Two Conjugate forme : 

 A [Mougeotia), showing for- 

 rnaMon of zygote in conjuga- 

 ting tube; B, C {Gouafone- 

 i/ia), sho\\'ing formation of 

 zj-gote \:'itliout conjugation. 

 —After WiTTRocK. 



