186 PHlTU^r IV. SIPHONOPHYCEAE 



spore eventually forms a wall around itself, and then 

 proceeds to elongate into a new plant-body. 



271. Generation takes place in special, usually lateral, 

 segments. Both antherids and oogones develop as pro- 

 tuberances upon the stem. The antherid is long and 

 rather narrow, and soon much curved; its upper portion 

 becomes cut off by a partition, and in it very small bi- 

 ciliated sperms are developed in great numbers. The 

 oogone is short and ovoid in outline, and usually stands 

 near the antherids. In it a partition forms at its base; 

 the upper portion becomes an oogone, and its protoplasm 

 condenses into a rounded body, the egg. At this time 

 the wall of the oogone opens, and permits the entrance of 

 the sperms which were set free by the rupture of the 

 antherid wall. 



272. Upon coming into contact with the egg one sperm 

 fuses with it; the fertilized egg (zj^gote) immediately 

 begins to secrete a wall of cellulose about itself, and it 

 thus becomes a resting spore. After a period of rest the 

 thick wall of the resting spore splits, and through the 

 opening a tube grows out which eventually assumes the 

 form and dimensions of the full-grown plant. 



Here must be placed half a dozen families of hystero- 



phytic plants, the ''Tube Fungi," often known as the 



''lower fungi," and to be regarded as degen- 



j{i erate descendants of some such holophytic 



' form as Vaucheria. 



273. The Water-molds {Saprolegniaceae) 

 are colorless saprophytes or parasites. They 

 are generally to be found in the water, 

 Saproiegnia. attached to the bodies of living or dead 

 fishes, crayfishes, etc., or in decaying animal 

 or vegetable matter, in or out of the water. The plant- 

 body is greatly elongated and much branched, and is 



