LACTARIAE OF THE UNITED STATES 11 
(Bull. Fr. is nearly white when growing in dense shade but in a 
more exposed place it varies from yellowish-salmon to fulvous. 
In Г. /actiffua, however, which varies greatly in color, I have not 
been able to detect any fixed relation between coloration and light. 
It is thus probable that color depends upon the interaction of a 
number of factors, and any one factor may not have the same 
effect upon color in two different species. Іп Tricholoma Rus- 
sula, Bourquelot * was unable to find an oxidase ferment, yet color 
changes occur in the broken flesh, hence it seems possible that in 
some cases the action of the air alone is sufficient to cause a color 
change. Thus far, two oxidases have been identified in the mush- 
rooms, tyrosinase and laccase, both of which occur in the Lactar- 
iae. No work has been done along this line upon the American 
species of Lac/aria, and much investigation is needed before the 
chemistry and physiology of the genus will be understood. 
The accompanying analysis of three species of Lactariae by 
Margewicz is taken from Schenck's Handbuch der Botanik (4: 
391. 1890) The analysis was made from fresh young speci- 
mens. Bourquelot has made a study of the carbohydrates in sev- 
eral species of Lac/aria. With the exception of 2. /асийиа (L.), 
which contained volemite, mannite was present in all the species 
which he tested in the dried state. He found that the proportion 
of carbohydrate varies in different plants and in different specimens 
of the same species and that drying produces important differences 
both in the proportion and the nature of the substances. In Г. 
piperata the trehalose disappears and is replaced by mannite. In 
other species the glucose which is present as a trace in the fresh 
plant is found in large proportions in the dried plant. Bourque- 
lot's + analysis differs from that of Margewicz. From Gerard’s { 
studies of the oils in 2. ve//erea апа Г. piperata, we find that the 
former contains stearic acid, and the volatile acids, formic, acetic, 
and butyric, while oleic acid is present in a free state. Lecithine 
is probably present. 
* Bull. Soc. Myc. Fr. 13: 65-72. 1 
+ Bourquelot, Е, Matiéres sucrées continues dans les champignons, Bull, Soc. 
Myc. Fr. 8: 196-208. 1892; Les matiéres sucrées chez les lactaires. Bull. Soc. 
Myc. Fr. 5: 143-163. 
E 
1880. 
i Sur les matières grasses de deux champignons. Bull. Soc. 
Myc. Fr. 6: 115-128. 1890. 
