8 LACTARIAE OF THE UNITED STATES 
the ZLactariae in California and Oregon to form а basis for 
generalization. 
The species of trees growing in a forest, then, seem to be the 
greatest factor in determining what species of Lacfarta shall grow 
there. In oak or chestnut woods one may be sure of finding Z. 
lactiffua L. and L. piperata (L.) Fr. ; in beech woods, L. cinerea Peck 
and often Г. ve//erea Fr. ; in hemlock woods, Г. deliciosa (L.) Fr., 
L. subpurpurea Peck, апа Г. deceptiva Peck; other species seem 
to grow in any fairly moist deciduous forest. This limitation of 
species to the vicinity of a particular species of tree is undoubtedly 
largely due to the adaptation of the humus there found to the 
growth of the fungus. Bourquelot * claims to have found іп Z. con- 
troversa Fr., which grows atthe foot of poplars, a ferment analogous 
to emulsin, which might indicate a symbiotic relation between the 
two. He was not able to find such a ferment in Z. vellerea Fr. 
Noack T states that he found a mycorhiza relationship between L. 
piperata (L.) Fr. and Fagus silvatica and Quercus pedunculata, 
also between L. vellerea Fr. and the beech. 
THE STRUCTURE, INTERNAL MORPHOLOGY, AND PHYSIOLOGY OF THE 
SPOROPHORE, INCLUDING COLOR CHANGES AND 
REACTIONS 
The Lactariae and Russulae are characterized by a vesiculose 
structure, that is, by the presence of parenchyma-like cells scat- 
tered among the filamentous hyphae. Fayod | designates these 
tissues as fundamental, consisting of isodiametric sphaerocysts, and 
connective tissue or slender hyphae. The sphaerocysts are 
grouped in the filamentous tissue, and DeBary § suggested that 
they might be enlarged branches of these hyphae constricted at 
rather regular intervals, so that the branch might be compared to 
a rosary. The sphaerocysts are sometimes grouped so as to 
appear in a cross-section of the stem like a rosette, the center of 
the rosette being the cross-section of a thin-walled tube which pur- 
* Bourquelot, E. Présence d'un ferment analogue à l'émulsine dans les cham- 
pignons et en see dans ceux qui sont parasites des arbres ou vivent sur le bois. 
Bull. Soc. Myc. 54. 
T Ueber darin s t Pilze. "Bot. Zeit. 47: 389. 1889. 
f Ann. Sci. Nat. Bot. УП. 9: 322-330. 1889. 
4 Morph. Fung. Mycet. and Bact. 298-301. f. 756. 1887. [Engl. transl. ] 
