410 Canadian Record of Science 



imperceptible beginning of the forking to long 

 colorless processes which were always found in 

 contact with other filaments or with masses of slime. 

 An examination of a large number of specimens showed 

 that only the end cell was thus affected, though the cell 

 next to it might lose some of its chlorophyll. These 

 root-like processes were continuous with the end cell, 

 they appeared to have a slightly laminated cell-wall, and 

 usually showed a sort of mucilaginous excretion with 

 which bacteria were frequently associated. 



An examination of material preserved from the 

 same aquarium in October showed that a few of the 

 filaments had possessed these branches when collected, 

 although in a less developed stage. Several other cul- 

 tures of Spirogyra from different localities showed the 

 same phenomenon, but it appeared in every case to be 

 the same species, other species in the same aquaria 

 showing no trace of the rhizoid-forming tendency. 



From these observations, and after a number of ex- 

 periments with various culture media which appar- 

 ently did not effect the form in any definite way, I 

 concluded that this tendenccy to form root-like pro- 

 jections must be a specific response to some physio- 

 logical stimulus which occurs in nature as well as 

 under artificial conditions. In Borge's "Uber die 

 Rhizoidenbildung" 15 it is stated that rhizoids can 

 be produced in Spirogyra filaments by the action of 

 certain culture media. After citing various instances 

 where the phenomenon of rhizoid formation has been 

 observed in certain members of the Chlorophycese, which 

 are ordinarily not supposed to possess these organs, 

 Borge describes a large number of experiments which he 

 made in order to study the cause of its occurrence. 

 He found that, when grown in a number of culture 

 media, such as cane-sugar, asparagin, agar-agar and 

 glycerine solutions, Spirogyra fluviatilis could be in- 

 duced to form rhizoids, while in pure water cultures it 

 did not. This species, as well as two others, which 



