ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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species belonging to tbe Fumariacem. With the exception of berberine, 
no instance is known of a true alkaloid occurring in two species belong- 
ing to different natural orders. 
(3) Structure of Tissues. 
Spring and Autumn Wood.* * * § — According to M. E. Mer, the distinc- 
tion between spring and autumn wood is by no means so definite as is 
often stated, the wood formed in one season having, under special 
conditions, the general characters of that ordinarily formed in the other 
season. Moreover a zone of precisely the same character as that known 
in conifers as autumn wood, and formed about August 15, is formed in 
the oak about the middle of June. The zone usually called autumn 
wood should rather be called summer wood. The distinction between 
the two zones is very conspicuous in woods with large vessels, less so in 
conifers. 
Collenchyme. I — A series of observations made by Herr J. Cohn on 
the structure and function of collenchymatous tissue lead him to the 
conclusion that the functions ascribed to it of conducting and of 
storing up water rest on incorrect observations. Its only purpose which 
at present has been fully determined is a mechanical one. In its living 
state the cell-walls of a collenchymatous tissue contain as much as from 
60 to 70 per cent, of water, while lignified phloem and xylem contain only 
from 20 to 40 per cent. ; but after drying, collenchyme has no greater 
power of absorbing water than woody tissue. The water is deposited 
chiefly in the radial direction, to a certain extent in the tangential, least 
of all in the longitudinal. The innermost grey layer contains the 
largest proportion. A specially extensible collenchyme was observed 
in Rheum and Malva. 
Sieve-tubes of Papilionacese.J — Dr. P- Baccarini describes a struc- 
ture which he finds very widely distributed among the Papilionaceae. 
In the middle of the cavity of the sieve-tubes is suspended a gelatinous 
mass, usually of a polygonal form, and lying on one side of the tube, 
but connected with the peripheral protoplasm of the other side by 
delicate threads. The structure presents the ordinary reactions of tbe 
gelatin of sieve-tubes. Its origin varies; in some cases the nucleus 
takes no part in its formation, while in others it is derived directly from 
the protoplasm which envelopes the nucleus, and from the nucleus 
itself. 
Caoutchouc cells of Eucommia.§ — Prof. F. E. Weiss describes the 
caoutchouc-containing cells in this plant, of uncertain systematic 
position, from China. They are very elongated tubes, quite unbranched, 
and occur in the inner portion of the cortex, in the secondary phloem, 
and to some extent in the pith. They differ from the latex-cells of the 
Euphorbiaceae in containing only a single nucleus, and in arising 
de novo in all secondary growths, such as the secondary phloem, and in 
new shoots and leaves. During the early stages of their growth, the 
* Comptes Rendus, cxiv. (1892) pp. 501-3. 
t Jahrb. f. Wiss. Bot. (Pringdieim) xxiv. (1892) pp. 145-72 (2 figs.). 
X Malpighia, vi. (1892) pp. 53-7. 
§ Trans. Linn. Soc. Lond. (Bot.), iii. (1892) pp. 243-54 (2 pis.). 
