Olive—Occurrence of Oscillatoria Prolifica . 12*^ 
temperature and sunlight. During the year in which the plant 
was most abundant, it did not entirely disappear during the 
winter, but was found imbedded in the ice which was cut from 
the water. During the period of most rapid growth—generally 
in June—the water of Jamaica Pond frequently became turbid 
and opaque. I have myself noted, some years ago, that from the 
hills above, the water of this pond appeared reddish or of a 
brownish chocolate color in bright sunlight. .The authors state 
that after a hot, sunny day, the gas created by the vigorous 
: growth of the plant often caused the alga to rise to the surface 
:and there float as a reddish brown, frothy cream; on June 11 
and 12, 1901, for example, the floating masses were of such 
abundance that fully “one hundred barrels might easily have 
been obtained” (01, p. 308). When this scum was driven by 
the breezes on the shore, it decayed on the rocks, giving to them 
a rich purple coating. The odor of decay was “intensely dis¬ 
agreeable, fetid rather than putrefactive” (01, p. 301). 
The authors assert that, whenever the plant was found below 
the surface, it was blue-green in color; the red pigment, which 
they have tentatively named “rubescin” (04, p. 274), according 
to their observations, appeared in the filaments only when a 
luxuriant growth of the plant had taken place. They suggest 
the theory that the red substance is probably “an important 
factor, if not the chief one, in the vigorous growth of plant 
life.” (04, p. 274). The authors, in reaching this conclusion, 
apparently assume that this red pigment is derived from the 
chlorophyll of the Oscillatoria. They further bring in for com¬ 
parison the association of the red coloring matter in the young 
shoots of oak, maple, etc., with the vigorous growth of these 
shoots; and, from the a pparent close chemical relation of the red 
color in plants to the haemoglobin of animal blood, they conclude 
that “good red blood and a portion of red in the chlorophyll of 
green plants wherever found seem to indicate robust life.” (04, 
p. 274.) 
According to their further investigations, the optimum tem¬ 
perature for the growth of the alga iies between 64° and 66° F. 
After a season of such favorable conditions, a vigorous growth 
usually culminated in one or two days, never more, when large 
