10 LACTARIAE ОЕ THE UNITED STATES 
essary for the formation of the glycogen is carried through the 
filamentous hyphae and that later the nourishment returns along 
the same route to the hymenium as it is needed. Errera further 
suggests that the filamentous hyphae are elements of support. 
This can be true, of course, only in an elementary way. 
The cause of the change in color of the latex of certain species 
of Lactariae has been somewhat recently studied Бу Bourquelot 
and Bertrand.* They came to the conclusion that the phenom- 
ena of coloration are often due to the presence of an oxidizing 
ferment in the cells which acts upon a particular chromogen con- 
tainedin the mushroom. Only two out of twenty species examined 
showed the absence of ап oxidizing ferment. These were L. sub- 
dulcis (Bull.) and Г. mitissima Fr. When the latex changes color 
this chromogen is in solution in it and the oxidizing ferment con- 
cealed also in the solution acts upon the chromogen as soon as 
they come together in the air, as in the case of a wound, thereby 
changing the chromogen bodies into а colored pigment. It is to 
be assumed that in such species as Г. deliciosa (L.) Fr. the mush- 
room is so rich in oxidizing substances that this color change will 
result in the outer layers of cells. This view is upheld by the fact 
that when a leaf adheres firmly to the surface the epidermis is 
frequently colorless. The latex in the Dapetes is either colored in 
the living plant or the change takes place so instantly when the flesh 
is broken that one cannot perceive it. If the color is present in 
the latex while within the plant, it is possible that the oxidizing 
ferments are able to use the oxygen which enters the plant by res- 
piration. If this theory should be true we might expect variations 
of color under different temperatures and light conditions,+ since 
these factors affect the respiration of the mushroom. But while 
it has been shown that light diminishes respiration, certain species 
are brighter-colored when growing in open woods. Z. theiogala 
* Bertrand, G. Bull. Soc, Chim. Paris 111. 15: 793. 1896. 
Bourquelot, E. & Bertrand С. Les ferments oxydants dans les champignons. 
Bull. Soc. Myc. Fr. 12: 18-26. 1896; Sur la coloration des tissus et du suc de cer- 
tains champignons au contact de l'air. Bull. Soc - Myc. Fr. 12: 27-32. 1896. 
Bourquelot, E. Sur la présence générale, dans les champignons, d'un ferment 
oxydant agissant sur la tyrosine ; sur le mécanisme de 1а coloration du chapeau de ces 
végétaux. Bull. Soc. Myc. Fr. 13: 65-72. 1897. 
f Bonnier & Mangin. Ann. Sci, Nat. Bot. VI. 17:210-302. 1884. 
