106 ON THE PLANT-CELL. 



impossible immediately that endosmosis is in any way arrested. 

 The cell is then gradually destroyed by the action of the atmo- 

 sphere, and decays, though in different ways as it is exposed occa- 

 sionally or constantly to the action of water. The causes of 

 this death may be various laceration (as in the sporangia of the 

 Cryptogamia on the escape of the spores), complete dryness, removal 

 from the situation in which alone endosmosis is maintained (as in 

 the fall of the leaf), &c. 



The process of dissolution of a dead cell does not belong to Botany ; 

 we willingly commit the inquiry jnto it to Chemistry, and refer to the 

 latest and best works on the subject, byBerzelius*, Liebigf, and Mulder J. 

 The causes, however, which expose vegetable-cells to these destructive 

 influences are of interest to us ; and we may name among them, as a 

 very general one, the impossibility of endosmosis. Every vegetable-cell 

 which can no longer take up fluid, in order to maintain the chemical 

 processes within it, necessarily dies. Complete desiccation acts in the 

 same way ; and also the disruption of the cell, in consequence of which 

 isolation of the materials contained takes place, and the processes going 

 on within it cease. A peculiar state connected with this, is exhibited in 

 most of the cells which are separated from a plant in the form of leaves. 

 At the time of separation they are evidently not yet dead, for, under a 

 very favourable though extremely rare conjunction of circumstances, a 

 new process of vegetation may commence in one cell or another, in such 

 a way that an entirely new plant is thence produced. Commonly, how- 

 ever, they die altogether, it being no longer possible for them to take 

 up fluids, which had previously been brought to them in consequence of 

 their connection with the entire plant. 



SECTION II. 



LIFE OF THE CELL IN CONNECTION WITH OTHERS. 



50. As soon as the cells are associated so as to constitute 

 tissues, they exhibit certain modifications in their vital processes, 

 and these modifications are especially worthy of consideration. 

 Much of what relates to this part of the subject has necessarily 

 been touched upon in former sections, as we are not yet sufficiently 

 advanced to be able to comprehend with absolute precision the 

 individual cell-life, and thus in many things that occur do not 

 know how much or how little is due to the influence of the con- 

 tiguous cells : much, also, that is undoubtedly referable to the 

 combined action of several cells has necessarily been adduced, as 

 serving to explain the nature of the individual cells. What we 

 have now to consider are, first, the modifications which universally 

 take place in the life of cells in consequence of their being asso- 

 ciated ; and afterwards, the special peculiarities incidental to the 

 different tissues. 



* Lehrbuch der Chemie, latest edition, vol. viii. f Organic Chemistry. 



\ Physiologische Chem. (Moleschott), p. 146, et seq. Translated into English, by 

 Fromberg. 



