1889.] Botany. 911 
mroph oi pyrolusite after manganite, has been obtained by Gorgeu^ 
upon heating crystals of the latter mineral to a temperature of about 
300°. Dick 21 finds the kaolin from near Porth-yr-hwch, Anglesey, 
to be monoclinic, with a: b: <r=.5748: i: 4.7267, and the face 
00 Px) , 00 P, P, oP prominent. Its specific gravity is 2.62, and compo- 
sition : SiO,=46.53, Al203=38.93, Hp=i4.54. Des Cloizeaux" 
pronounces the mazapilite of Koenig to be orthorhombic. 
BOTANY. 
On the Hypophyllous, Epiphyllous, or Amphigenous Habits 
of Uredineae. — Whether the Uredinece are hypophyllous, epiphyllous, 
or amphigenous is, I think, determined largely by the character of the 
leaf. On those leaves which have stomata on the lower surface only, 
they are with few exceptions hypophyllous. They seem to normally 
infect the lower surface of the leaf, and spread in age, or in later stages, 
Taking Dr. Burrill's pamphlet on the Uredinece as a basis for estima- 
hundred and thirty species there given only three are epiphyllg)us, and 
these furthermore are frequently amphigenous. By far the greater 
number of species are hypophyllous only, while still a large number 
are amphigenous (about 48 amphigenous to 74 hypophyllous). Of the 
forty-six species and varieties of ^cidium all are hypophyllous but 
three, and these are amphigenous. This fact indicates that the teleu- 
tospores and their sporidia, when they germinate in the spring, must, 
in almost every case, enter the tissue of the host-plant through .some 
stoma on the lower surface of the leaf. irres]jective of whether the 
stomata occur on the upj^er surface also nr not ; and that here, in the 
looser soft tissue of the Idwci- surface, more slieltered from the sun 
^. iW/«.,XI.,p. 196. 
Vlay, 1888. p. 15. 
d. Min., XII., p. 441- 
