88 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



The three methods just given practically answer all require- 

 ments for marine algae. There are no fresh water algae that 

 will require the first method; a few (Cladophora, Oedogonium) 

 are best treated by the second, but the greater part require 

 the third. 



In collecting fresh water algae it will be found to be the rare 

 exception that a species can be recognized in the field ; one 

 must sample everywhere ; at first the abundance of new forms 

 will be so great that a few such samplings will give materials 

 for hours of study ; later, as one is more familiar with the flora 

 of a region, the proportion of novelties becomes smaller, and 

 after a while one is satisfied if only nine out of ten collectings 

 are thrown away after a hasty examination. On the other 

 hand, one will often find in a small bottle of material enough 

 forms for days of study. In such families as the Zygnemaceae 

 and Oedogoniaceae only fruiting specimens are accurately 

 determinable ; in all but a few of the larger forms the micro- 

 scope is needed to decide as to the presence or absence of 

 fruit. One must continue to collect, though the proportion of 

 prizes will grow steadily less. As a partial recompense, one 

 often finds minute epiphytic algae attached to the larger sterile 

 plants and minute plankton forms lying loose among them. 

 These minute unattached forms are very interesting, and have 

 been studied but little in this country. Wonderful collections 

 can sometimes be made by drawing a fine net through the 

 water, but a surprising variety can also be found entangled 

 among Utricidaria and other water plants, or adhering to the 

 gelatinous coating on stems and leaves of Pontcderia, Brasenia, 

 etc. In the latter case the material can be scraped off ; in the 

 former it is better to squeeze the plants thoroughly, remoisten 

 and again squeeze ; this can be repeated many times before the 

 supply of algae fails. If the liquid stands in a jar or bottle, in a 

 few hours the algae will settle to the bottom ; the liquid can be 

 drawn or carefully poured off. If then formalin be added, 

 enough to make the liquid a three per cent, solution, the ma- 

 terial can be studied at leisure. 



The effect of formalin is not permanent, and where perma- 

 nence is needed, other preparation must be used. The technic 



