151 



or gives the look of scum as the pollen does. During my 

 visit to Chilson Lake in 1901, going as I did in the middle of 

 May, I kept the phenomenon in mind and was on the watch for 

 it, and singularly enough it was on the 14th day of August that 

 I first saw it. Water was taken and slides made. I left the 

 lake September 15th, making slides from water taken on the 7th. 

 How much longer the alga continued I cannot say." 



Further observations by Mrs. Smith at Chilson Lake in the 

 summers of 1902 and 1903 indicate, as might be suspected, that 

 the interesting little alga has no fixed prejudices for the 14th of 

 August as the date for its initial appearance. In 1902, it was 

 first seen on July 26 and Mrs. Smith writes that in 1903 " it was 

 in the lake June 6 when we arrived." 



The alga in question, judging from well preserved specimens 

 from Chilson Lake, collected by Mrs. Smith at various times in 

 the summers of 1901 and 1902, is apparently the plant known 

 to some as Rivularia echinulata (Sm.) or Rivularia fluitans 

 Cohn, to others as GloiotricJiia Pisuvi (Ag.) Thuret, and more 

 recently, as GloiotricJiia echinulata (Sm.) P. Richt. It may be 

 remarked, in passing, that the generic names Rivularia and Gloio- 

 tricJiia, in their current sense, are both invalid under the provi- 

 sions of the Paris and Rochester codes, but a note like the present 

 is hardly the place for introducing names that may be new or 

 unfamiliar. The Chilson Lake plants form small colonies mostly 

 about 1 mm. in diameter, but ranging from 0.5 mm. to 1.5 mm. 

 These colonies are usually spherical, rarely reniform or somewhat 

 horseshoe-shaped. The color in mass, when suspended in a 

 fluid (a mixture of one per cent, chrome-alum and one per cent, 

 commercial formalin was used for preservative) is a light bluish- 

 green. In the younger stages, the radiating whip-like filaments 

 which form the colonies are easily separable, but as the colonies 

 get older and the filaments become more numerous, the globular 

 masses become firmer in consistency and the component parts do 

 not separate readily under pressure. Unfortunately, no spores 

 (or, at most, only slight suggestions of the beginning of spore- 

 formation) have been found, though Mrs. Smith's collections 

 were made as late as September 7, in 1901 ; and the determina- 



