142 
for 1836 have,also,reached us, contains many interesting and important commu¬ 
nications on various subjects connected with Natural History. Of those which 
strike us as most practically useful, we shall render an account in the next Num¬ 
ber of the Naturalist. The work is edited by Dr. Wiegmann ; and published 
at Berlin. It is, at present, only in its second year. The three Numbersbefore 
us are enriched by eight very delicate, and apparently most accurate engravings. 
EXTRACTS FROM THE FOREIGN SCIENTIFIC JOURNALS. 
1.—On the Silex of Plants. Mr. G. A. Struves, of Dresden, has 
recently published a dissertation on the silex found in some species of plants. He 
assumes as a principle that lime is necessary to the animal kingdom, and silex to 
the vegetable ; that certain localities are the more abundant in the different 
species according to the prevailing nature of the soil. Silex being almost insolu¬ 
ble, and not able to penetrate vegetables which are not aquatic, necessarily exists 
in larger proportions in those species circulating water. Mr. Struves concludes, 
from his experiments, that the silex discoverable in plants owes its presence to the 
action of the water absorbed by the plant, that it is not combined either with an 
acid or an alkali, and so far predominates over the other chemical components as 
to determine the form of plants. 
The following are the numerical results of Struves’s analyses :— 
Silex. 
Alum. Salts. 
Calcareous. 
Manganese. 
Equisitum hvemale . 
. 97,52 ... 
. L7 . 
. 0,69 . 
. 0,0 
Equisitum limosum. 
. 94,85 ... 
. 0,99 . 
. 1,57 . 
. 1,69 
Equisitum arvense . 
...... 95,48 ... 
. 2,55 . 
. 1,64 . 
. 0,0 
Spongia lacustns .. 
. 94,66 ... 
. 1,77. 
. 0,99 . 
. 2,0 
Calamus Rhodan ? . 
. 99,20 ... 
. 0,0 . 
. 0,54 . 
. 0,0 
We beg leave to observe that the plants above experimented upon all belong 
to the class monocotyledon, long known to secrete silex, if we may be allowed the 
expression ; but Mr. Struves appears to think the same circumstance may be 
traced throughout the vegetable kingdom: in which we cannot concur, it being 
well known that a very small portion of silex can be detected in the c&cotyledonous 
class. We also confess no small astonishment at finding the analysis of a sponge 
classed with vegetables, its animal claim having long since been clearly established. 
We have placed a query to Calamus Rhodan, not knowing the plant by that name. 
