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BIOLOGY: GENERAL AND MEDICAL 



gium containing a zoospore which escapes by rupturing 

 the apex of its wall by means of a rotary motion. This 

 zoospore is large enough to be seen with the unaided eye, 

 consists of mass of colorless protoplasm containing nu- 

 merous nuclei and is surrounded on all sides by cilia, two 

 of which are given off opposite each nucleus, and is said 

 by Strasburger to correspond to the collective individual 

 zoospores of an ordinary sporangium. This zoospore 



FIG. 74. Sexual reproduction of the green felt (Vaucheria). A, Vaucheria 

 sessilia; o, oogonium; a, antheridium; os, the thick-walled oospore, and beside 

 it an empty antheridium; B, Vaucheria geminata, a short lateral branch develop- 

 ing a cluster of oogonia and a later stage with mature oogonia o and empty 

 antheridium a; C, sperms; D, germinating oospore. (C, after Woronin; D, 

 after Sachs.) (From Bergen and Davis, "Principles of Botany." Ginn & Co., 

 publishers.) 



immediately develops into a new plant. In addition to 

 this and more important in this argument is the sexual 

 reproduction. From the same cell of one of the fila- 

 ments two small protuberances, the oogonium and an- 

 theridium, containing the female and male elements, re- 

 spectively, make their appearance and soon develop as 

 short lateral branches which become separated from 

 the rest of the thallus. It is said that the oogonium at 



