1902] MICROSCOPICAL JOURNAL. 83: 
slides which are at times furnished by members, they do 
not advance the best interests of the P. M. S. as slides of 
less perfect finish do, whose bona-fide touches and descrip- 
tions are instinct with the spirit of helpfulness. Even 
quotations from books, such as Carpenter’s, might form the 
groundwork of some interesting and practical communi- 
cations. “Light, heat, moisture; etc.,” in the formation 
of vegetable tissues, call up some of the most interesting 
problems connected with structural botany. For instance; 
what causes a double, or even a multiple, succession of 
rings to occupy the place of a single one, as ascertained 
by transverse sections of wood?—J. Birkbeck. 
Slides should not be circulated merely as objects of 
beauty. They mustconvey instruction. We are never 
tired of having described to us the beautiful devices 
which Nature adopts to build up the various natural ob- 
jects which surround us. There is, in truth, a very fine 
delight in the acquisition of scientific information new to 
ourselves, even if the information has been known for ages 
to others; and, further, those to whom these scientific 
facts may be well known never tire of having them 
brought fresh to their notice—especially if the old story 
be well told and illustrated.—J. R. L. Dixon. 
ARISTOLOCHIA CLEMATITS.—Shows the concentric and 
regular disposition of the vascular bundles in dicotyled- 
onous stems. It will be observed that the stem isa young 
one, as evidenced by the amount of pith, which in the root 
may be so much checked, as almost entirely to disappear. 
Ricinus ComMUNIS.—Shows a hypocotyle of this dicoty- 
ledonous plant. The vascular bundles consist of phloem 
externally and xylem internally, separated by a layer of 
cambium which is continued into the fundamental tissue 
lying between the vascular bundles as interfascicular cam- 
bium, The xylem contains vessels with narrow pits and 
vessels with broad pits with wood parenchyma between 
