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 hyemale 97,52 1,7 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 lacustris 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 rwonocotyledon, 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 cfc'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. 



