2 4 BOTANICAL GAZETTE - [january 



Summary r 



i. Few of those who have published papers on the genus Spirogyra 

 have given any notes on the subject of periodicity. 



2. Out of 700 aquaria it was found that the best way to arrange 

 a culture was to place some sterilized earth in the bottom, add some 

 dead leaves or dead grass, allow to settle well, then add a small amount 



irogyra, and place at first in a window not exposed to direct 



sunlight. 

 3- 



time 



most 



about 5 per cent, which contained conjugating material. The time 

 corresponded with that of the field. 



4- Leaving out of account the number of species which may have 

 been collected in the vegetating condition and for that reason doubt- 

 fu of identification, there were at .least thirteen different species 

 collected, of which twelve fruited more or less abundantly. 



5- Ten of the thirteen species passed their period of maximum 



May, one in August 



doubt 



Hantzschii 



August The only reliable example of a second fruiting period found 

 was 5. «», which fruited in May, and again in small patches, but 

 relatively abundant, during the latter part of July 



6. When field-work was first begun, material was collected and 

 then brought to the laboratory for examination. This method was by 

 no means satisfactory and for that reason was discarded. All the 



7 



microscope 



maximum abundance corresponds in every 



" * pc "° u OI ■ nax 'm«m conjugation. The decline of one was 



always accompanied by that of the other. 



nJ; TT COnjU f at r had ceased the fruiting filaments disappeared 



ZZ 1 K * ^ The V6getative filamen ^ ^ disappeared, 

 and at the same time as those containing zygospores. 



but'il™ ^ T^ r Spir0gyfa WaS f ound f ™ itin « a ' the surface 



5 to7Z H ^ rV UbStratUm - In ' he fidd the r — ™ t™. 

 To T>1 t ; HantZSCkii ' hOWeTCr > werc P^nent exceptions. 

 . 1„ • , h ', rteen Species one has ^t been found in a state of 



conjugation. 



observation 





