PHTC0PH7TA. 151 



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. 



268. The Water-moulds [Saprolegniacem) are colorless 

 saprophytes or parasites, more frequently the latter; they 

 are generally to be found in the water, attached to the 

 bodies of living or dead fishes, crayfishes, etc., or occasion- 

 ally in the moist tissues of animals out of the water. The 

 plant-body is greatly elongated and branched, and all its 

 vegetative portion is continuous; the reproductive portions 

 only are separated from the rest of the plant-body by 

 partitions. 



269. The asexual reproduction is very much the same- 

 as in green felt. It may be briefly described as follows : 

 The protoplasm in the end of a branch becomes somewhat 

 condensed, a partition forms, cutting off this portion from 

 the remainder of the filament, and the whole of its contents 

 becomes converted by internal cell-division into zoospores 

 provided with one or two cilia (Fig. 79, 1). These soon 

 escape from a fissure in the wall and are active for a few 

 minutes, after which they come to rest and their cilia dis- 

 appear (3 and 3). In one or two hours they germinate by 

 sending out a filament (4), from which a new plant is 

 quickly produced. 



270. The sexual organs also bear a close resemblance to 

 those of green felt. The oogones are spherical, or nearly 

 so (in most of the species), and contain from two to many 

 germ-cells, which are fertilized by means of antherids, 

 which usually develop as lateral branches just below the 

 oogones. In some species the antherids and oogones are 

 upon the same plants, and in such cases the fertilization 

 takes place by the direct contact of the antherid and the 



