COMMON POND SCUM. 



Spitogyra quinina Kiitz. 



PRELIMINARY. 



THE members of this genus are abundant in stagnant 

 water everywhere, forming bright yellow-green scums of 

 great extent, sometimes diffused beneath the surface, or 

 in running water attached to stones. They may be read- 

 ily distinguished from all other scum-producing plants, 

 except from a few of their close allies, in having a slip- 

 pery feel, and being composed of long unbranched fila- 

 ments, which string out like wet hair when withdrawn 

 from the water. The allied kinds, which can not be 

 separated by this simple test, will at once be distin- 

 guished when placed under the microscope by possess- 

 ing no spiral chlorophyll bands as in Spirogyra. When 

 growing vigorously the masses of Spirogyra are an 

 intense light green ; when beginning to fruit they turn 

 brown, and look very uninviting ; but as the characters 

 which distinguish the species are largely drawn from 

 the fruiting condition, the collector soon learns to 

 regard these unsightly objects with favor. 



The vegetative condition may be found at any time 

 during the warmer portion of the year. The fruiting 

 condition occurs from early spring to June and July, 

 and sparingly during the remainder of the warm season. 



The species usually grow intermixed, and almost any 



