377 



quantity of sediment and forms than in the instance where one hour and 

 twenty-five minutes was required for filtration. Some permanent slides 

 were prepared in 1S96 and part of these I still have, which show some of 

 the various Alg?e forms obtained by the method above referred to. These 

 slides were prepared by making a mounting fluid of the following sub- 

 stances : 



Alcohol. 95% 10 ccm. 



Glycerin 30 " 



Distilled water 30 " 



Acetic acid, 5% 30 " 



Specimens mounted in this mixture should be sealed with balsam. 

 The slide should be thoroughly cleansed and dry before ringing the cover- 

 glass with balsam. The only danger from the loss of specimens so mounted 

 is from the liability of the balsam to crack and allow the liquid under the 

 cover-glass to evaporate. For this reason they had better have the balsam 

 covered with a layer of dammar-lac or shellac, and be noticed from time 

 to time and not kept in too warm a place. 



Dilute glycerin seems also to be a good medium for mounting Alga>. 

 One specimen of Pandorina has been preserved and mounted in it fifteen 

 years and is still apparently as green and as perfect as the day it was 

 mounted. Camphor water 1 and glycerin also seem to give good results 

 from the standpoint of preservation. 



Other forms of the Algse of this list not found in the water works 

 reservoir have been observed at different times and recorded as found. 

 It is not supposed that this list of Algse here given is by any means com- 

 plete, but gives an idea of a few out of an enormous number of forms that 

 must be widely distributed. A good many of the forms here mentioned 

 have been found by Mr. A. B. Williamson, one of the students in the Botany 

 Department, and reported to me for the following list. 



A list of the growing forms of plants in any locality is best made and 

 more complete when extended over a series of years, so as to include those 

 individuals which for various reasons or changes of conditions do not ap- 

 pear during one season. 



1 Stokes — Analytical Keys to the Genera and Species of the Fresh-water Algse, 

 p. 20. 



