172 VAUCHERIA AND CAULERPA LESS. 



water for some time by the vibration of its cilia (c 3 ). After 

 a short active life it comes to rest, develops a cell-wall, and 

 germinates (c 4 ), i.e., gives out one or more processes which 

 extend and take on the form of ordinary Vaucheria filaments ; 

 so that in the present case, as in Mucor (p. 164), the de- 

 velopment of the plant shows it to be, to all intents and 

 purposes, a single immensely elongated cell, which has 

 become multinucleate without any corresponding division of 

 the protoplasm. 



In its mode of sexual reproduction Vaucheria differs 

 strikingly not only from Mucor, but from all the organisms 

 we have hitherto studied. 



The filaments are often found to bear small lateral pro- 

 cesses arranged in pairs (o 1 ), and each consisting of a little 

 bud growing from the filament and quite continuous with it. 

 These are the rudiments of the sexual reproductive organs 

 or gonads. The shorter of the two becomes swollen and 

 rounded (D 2 ), and afterwards bluntly pointed (D S , ovy) : its 

 protoplasm becomes divided from that of the filament, and 

 a septum (D S , sep') is formed between the two : the new cell 

 thus constituted is the ovary. 1 The longer of the two buds 

 undergoes further elongation and becomes bent upon itself 

 (o 2 ), its distal portion is then divided off by a septum (D S , 

 sep) forming a separate cell (spy), the spermary. 2 



Further changes take place which are quite different in 

 the two organs. At the bluntly-pointed distal end of the 

 ovary the cell-wall becomes gelatinized and the protoplasm 

 protrudes through it as a small prominence which divides 

 off and is lost (o 4 ). The remainder of the protoplasm then 

 separates from the wall of the ovary and becomes a naked 



1 Usually called the oogonium. 



2 Usually called the antkeridium. 



