598 PROCEEDINGS OF THE ACADEMY OF [NoV. , 



A PECULIAR CONDITION OF (EDOGONIUM. 

 BY IDA A. KELLER. 



For several years I have kept a jar of water at my window, in 

 which I have found interesting things at different times. Last fall 

 there was a luxuriant growth of a dense green mat, which turned 

 out to be a species of (Edogonimn. Later on, as the color gradu- 

 ally disappeared, I took for granted that the plant was about to die, 

 and gave it no further attention. The next time I happened to 

 observe the jar the alga seemed to have been replaced by a heavy 

 growth of the mycelium of some fungus. This remained in a 

 thriving condition all winter, and proved on examination, to my 

 great surprise, not to be a fungus at all, but the Q^dogonium 

 which had lost its chlorophyll. In all other respects the alga Avas 

 apparently in a perfectly healthy condition, its filaments Avere 

 rooted fast to pieces of rock which were in the bottom of the jar, 

 the cells showed absolutely no signs of decomposition — further- 

 more, they were remarkably well packed with granules which 

 turned out to be starch. 



This phenomenon seemed to me an unusual one. I know of no 

 alga which continues to live after it loses its chlorophyll, nor can 

 I recall any parallel case among the higher plants — a water-plant 

 which ceases its assimilating activity, full of the most attractive 

 bait for bacteria, in nowise protected from them, and yet of suffi- 

 cient vitality to withstand all attacks of these ever-present enemies. 



The condition of the plant in May may be summed up as fol- 

 lows: The filaments are rooted to pieces of rock. To the naked 

 eye they seem perfectly colorless and form a dense tuft of white 

 threads. Fig. 1 represents a typical case. It shows absolutely no 

 sign of chlorophyll and is full of starch. 



In fig. 2 I have represented what may be regarded as a transi- 

 tion stage. It is also full of starch, but the cell has a faint green- 

 ish tinge. It is impossible to say whether the plant is just regain- 

 ing its chlorophyll or whether it is just losing it. 



