82 THE AMERICAN MONTHLY [Apr 
ma-sheath of Aristida fasciculata which occurs in some 
other species of the genus and not by any other genera 
examined. It no doubt constitutes a generic character. 
It is not due to environment and such species of the ge- 
nus that do not possess this double sheath should be re- 
moved from the genus proper and especially so because 
their morphological characters are so distinct. Interest- 
ing are his observations that it does not seem as if any 
special type is characteristic either from the plains, the 
prairies or the fields. The Aristida fasciculata is thus 
associated with many and diverse types of Gramineae all 
of which have been classified as ‘‘Xerophytes.” Yet there 
is a similarity of structure among all of the types studied 
from plains, fields and swamps. The author thinks it is 
a mistake to establish such societies as xerophilous, hy- 
drophilous, etc., without having studied their structural 
peculiarities. The suggestions are certainly worth con- 
sidering in studying the ecological relations of plants. 
(Separate Beiheft. Bot. Centralbl 11: Heft 2. 1901). 
Extracts from Postal Microscopical Society’s Note—books. 
Edited for Science Gossip. 
SECTIONS OF StTEMSs.—These slides are intended as il- 
lustrations of the varieties that vegetable tissues take un- 
der the varying conditions of exposure to light, heat, and 
moisture, etc. Beginning with sections that illustrate the 
normal forms of the monocotyledon, the dicotyledon, etc., 
there follow modifications of these, some of which it would ~ 
be difficult to assign to any of these groups did there not 
exist other means of classification than that of structural 
arrangement. These different slides commend themselves 
to observers, if for nothing else than for the elegance of 
form which they present.— W. Pumphrey. : 
A very important factor in the P. M.S. is to cater for 
the learners ; and however excellent may be the dealer’s 
