MULTINUCLEATE. ■ loi 



numerous nuclei. Asexual reproduction is effected in 

 various ways. The tips of certain branches become swollen 

 and separated by a transverse wall or septum from the 

 remainder of the cell, the contents contracting and forming 

 a new cell by the method of rejuvenescence : after escaping 

 from the mother-cell the new cell either germinates at 

 once, or spends some time as a resting-spore. This method 

 of reproduction is said more especially to follow an 

 injury to the plant. Zoospores are formed in the tips of 

 branches which are separated from the cavity of the plant 

 by a septum, the contents contract and form a single large 

 zoospore completely surrounded by fine cilia ; after a brief 

 period of activity the cilia are contracted, a wall of cellulose 

 formed, and germination commences at once. The sexual 

 organs are produced laterally on the elongated wall, usually 

 on the same, sometimes on distinct plants. When developed 

 on the same plant, the antheridia and oogonia are usually 

 near to each other. The antheridia are formed at the tips 

 of slender, straight, or curved branches, and contain a 

 quantity of biciliate zoospores, which eventually escape 

 through the ruptured apex of the antheridium or mother-cell. 

 The oogonia originate as stout blunt swellings, which 

 eventually develop into elliptical or circular bodies, furnished 

 at the free tip with a narrow nipple-like prominence. Their 

 contents, like those of the antheridia, are separated from the 

 cavity of the supporting cell by a septum ; the contents then 

 contract to form an oosphere, which is exposed by the 

 deliquescence of the nipple-like apex of the oogonium. 

 Through this opening the antherozoids find their way to 

 the oosphere and coalesce with it ; the fertilized oosphere 

 secretes a cellulose cell-wall, assumes a red or brown colour, 

 and becomes a resting-spore. On germination, several 



