NOTABLE PHENOMENA. 115 
proceeds rapidly till the depth of intensity has been gained. 
This blue colour is so universally confined to dangerous species 
that it is given as a caution that all species which exhibit a blue 
colour when cut or bruised, should on no account be eaten. The 
degree of intensity varies considerably according to the con- 
dition of the species. For example, Boletus caerulescens is 
sometimes only very slightly, if at all, tinged with blue when 
cut, though, as the name implies, the peculiar phenomenon is 
generally highly developed. It cannot be said that this change 
of colour has as yet been fully investigated. One writer some 
time since suggested, if he did not aflirm, that the colour was 
due to the presence of aniline, others have contented themselves 
with the affirmation that it was a rapid oxidization and chemi- 
cal change, consequent upon exposure of the surfaces to the air. 
Archdeacon Robinson examined this phenomenon in different 
gases, and arrived at the conclusion that the change depends on 
an alteration of molecalar arrangement.* 
One of the best of the edible species of Lactarius, known as 
Lactarius deliciosus, changes, wherever cut or bruised, to a dull 
livid green. This fungus is filled with an orange milky«fuid, 
which becomes green on exposure to the air, and it is conse- 
quently the juice which oxidizes on exposure. Some varieties 
more than others of the cultivated mushroom become brownish 
on being cut, and a similar change we have observed, though 
not recorded, in other species. 
The presence of a milky juice in certain fungi has been 
alluded to. This is by no means confined to the genus Lac- 
tarius, in which such juice is universal, sometimes white, some- 
times yellow, and sometimes colourless. In Agarics, especially 
in the subgenus Mycena, the gills and stem are replete with a 
milky juice. Also in some species of Peziza, as for instance in 
Peziza succosa, B., sometimes found growing on the ground in 
gardens, and in Peziza saniosa, Schrad., also a terrestrial species, 
the same phenomenon occurs. To this might be added such 
species as Stereum spadiceum, Fr., and Stereum sanguinolentum, 
* Berkeley, ‘‘ Introduction to Crypt. Bot.” p. 266. 
