20 BOTANICAL GAZETTE [jantjary 



General conclusions 



In forming conclusions concerning whether any given plant passes 

 through a series of regular recurring phenomena, it is well to with- 

 hold positive conclusions until the plant in question has been carefully 

 observed for a number of successive seasons. This method of ap- 



time 



may 



plant can be studied from a number of varying < 

 ment. However valuable external conditions 

 any given phenomenon, it seems well not to overlook whatever influ- 

 ence may be due to internal conditions. There may be conditions 

 that cannot be seen, felt, weighed, or measured, that initiate and 

 support even the simplest plants through a series of complicated 

 phenomena. Notes on Spirogyra for this region seem to credit much 

 influence to internal conditions. Here were forty different places 

 in which this plant appeared, matured, and disappeared, in a single 

 season. Without a single exception the disappearance was imme- 

 diately preceded by a period of conjugation. Special importance is 

 given to the fact that in no case did all of the filaments enter into 







spore formation either with or without conjugation. It is to be 

 further noted that both the vegetative and conjugating filaments dis- 

 associated almost at the same time and disappeared, even from 



of surface. 



abundant over comparat 



Of the twelve species studied, ten were in fruit in May, and 

 in every case the maximum abundance of conjugation occurred within 

 this month. In a few nlacpe 



more 



forms grew 

 " maximum 



succeeding one another at intervals ranging from one to two weeks 



within 



species of Spirogyra were found growing together at three different 

 places at the edge of a slow brook. In two of the three places Spiro- 

 gyra was very abundant and covered an area in each of about 200 sqft . 

 Probably all had had the same source earlier in the year during 

 high water, but remained distinct until all had disappeared in June. 

 No fruiting material was found in either of the larger patches; two 



same 



