ALG.-E. 121 



that is to say, in a tank of sea-water. " Patches of 

 a rich crimson purple colour formed here and there 

 on the surface, which rapidly grew on all sides till 

 they coalesced. If allowed to be a few days undis- 

 turbed, the entire surface of the water became covered 

 with a pellicle of the substance, which spread also 

 over the stones and shells of the bottom and the 

 sides of the vessel. It could be lifted in impalpable 

 laminae on sheets of paper. I found it difficult to 

 keep it within bounds, and impossible to get quite 

 rid of it, till after some months, I lost it by the 

 accidental breaking of the vessel. Under the micro- 

 scope this proved to be an Oscillaria, the filaments 

 creeping and twining with the peculiar vermicular 

 movements of the genus." ^ 



Water Net. 



Certainly one of the most popularly interesting 

 of fresh-water alga; is the water-net, not only on 

 account of its singular appearance and comparative 

 rarity, but also for some of the features in its life- 

 history. It is well known that the water-net will 

 rather suddenly make its appearance in some quiet 

 water, where perhaps it was never known before, and 

 be found there for two or three years, when it will as 

 suddenly vanish, and the place will know it no more. 

 It was found, not many years ago, in a small pond, 

 less than half an acre in extent, in such profusion 

 that no water could be taken out which did not 

 contain it. Within three years most diligent search 



• "Romance of Natural History," by P, H. Gosse, vol. ii. p. 104. 

 (1861.) 



