INTERNAL STRUCTURE OF PLANTS. 
7 
pitates, are in many instances produced immediately ; at first 
they are flexible, become, however, brittle afterwards, and are 
changed also into flocculent masses. The fourth and last 
kind, are the gelatinous precipitates. Thus far the subject, 
properly speaking, does not belong to our department. The 
author, however, proceeds further. He reduces the molecular 
movement to an attractive and repelling power, and applies 
this to the movement of the granules in the cells, which he 
says may be explained in the same manner, even though it 
is assumed that the movement depends on the walls of the 
cells. He refers to the statement of Schwann, with regard to 
the manner in which the cellular bodies arrange themselves 
around a granule, and finds a similarity in the manner in 
which the granules form themselves in the precipitates. He 
carbonized pieces of an onion, the cells of which contained 
nuclei, and found the nucleus destroyed; but is still of opinion, 
however, that this negative result does not prove any thing. 
Carbonized parts of plants, it is well known, retain their 
original form, and the author therefore inquires, whether the 
formation of the homogeneous organic members may not be 
considered as a membranous precipitate of substances, which 
are usually termed inorganic. 
In the present year (1841) I have published a small treatise 
respecting the solidity of bodies, with the view of directing the 
attention of natural philosophers to this subject. I have seen, 
and proved it to several eminent natural philosophers, that all 
precipitates, when analyzed immediately after their formation, 
exhibit globules ; that these globules unite themselves to larger 
ones (being therefore fluid, like globules of quicksilver) ; and 
that these united globules or drops, subsequently only (and 
that frequently under our own eyes) change themselves into 
crystals. If M. Harting did not observe this, it was owing to 
his not having examined the precipitates speedily enough. 
The globules sometimes form flat surfaces, sometimes they are 
gelatinous. I have repeated, in this small treatise, what I 
have before stated, that all fluid substances exhibit a com- 
mencement of solidity on their surface — for we attribute 
fluidity to a substance, if the parts can be displaced from each 
399 
