(EDOGONIUM 423 



3. A single nucleus in each cell, which is, however, 

 difficult to recognize in well-nourished cells. 



4. A large central vacuole. 



II. An examination, of fresh filaments may result 

 in the observation of the reproductive organs, and 

 numerous specimens should be looked over with the 

 object of finding them. Thus the reproduction by 

 swarm-spores may be seen, especially in the 

 morning : without the cell having undergone any 

 change of form the cell-wall ruptures by a transverse 

 split, and the protoplasmic body, having previously 

 contracted, escapes through the slit as a motile pear- 

 shaped, primordial cell, the anterior end of which is 

 surrounded by a fringe of cilia. After a motile period 

 these attach themselves by the anterior end to some 

 firm body, and, forming a cell-wall, develop into new 

 filaments. Note young plants in early stages of 

 germination : they may be found in numbers attached 

 to submerged plants or stones in waters where 

 CEdogonium grows. 



III. There is some variety in the details of develop- 

 ment of the sexual organs in different species of 

 (Edogonium : some species are monoecious, others 

 dioecious. 



The oogonia, or female organs, are most easily 

 observed, being spherically enlarged cells of the fila- 

 ment, borne singly or several together : in such oogonia 

 note 



i. The rupture of the cell-wall at the period of 

 maturity by a transverse slit. 



ii. The beak-like canal, which projects in some 

 species from the slit. 



