232 Brown : Algal periodicity 



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in the smaller water-works pond, among a growth of Typha. It 

 was not seen there again but was found in a water-trough near by, 

 in which there was flowing water. It was rather rare here during 



May 



(Mesocarpus 



scalaris) was found in the upper waters of stream no. I, October I. 

 It was rather abundant and unhealthy looking and became more 

 rare and unhealthy the latter part of October and in November. 

 None was noticed after November I 5 until March 4, when a small 

 amount was found in an unhealthy condition ; it did not seem to 

 be growing any and had doubtless passed the winter in that condi- 

 tion. During May it began to grow and again became rather 

 abundant. Following this it became rare but persisted throughout 

 the summer. Small quantities of Mougeotia parvula {Mesocarpus 

 parvulns) were found in small pools of water in the upper part of 

 stream no. 1 in May. The water here was slightly stagnant, not 

 flowing freely. This was rather abundant in stagnant pools until 

 the first of August. 



Another filamentous form of the Conjugatae found was Mou- 

 geotia genuflexa [Plenrocarptts mirabilis). This was rather abun- 

 dant in the lower part of stream no. 2 during the latter part of Octo- 

 ber and in November. Many filaments were bent at nearly right 

 angles and the angles were united as if the cells were conjugating 

 but nothing to indicate the passage of cell contents was observed. 

 No spores were seen. On June 3 this plant was found floating in 

 the upper part of the larger of the water- works ponds, near where 

 it was found in stream no. 2. It was rather abundant and not very 

 healthy and seemed to be in an early stage of conjugation similar 

 to that which was seen in November. Later in the summer, this 

 species was found floating in, several places in both of the water- 

 works ponds. In every case certain cells were bent as described 

 . above and connected with similar cells in other filaments. The 

 plant always appeared to be unhealthy. 



Representatives of six genera of the family Desmidiaceae were 

 found but only a few species in each genus — one in some. Clos- 

 terium appeared to be the most abundant, both in quantity and 

 distribution, appearing in four different ponds. Clostcrium acerosum 

 was especially abundant in pond no. 2. Here it was noticed Oc- 

 tober 29, rather rare but in a healthy growing condition. It 



