ON THE DEVELOPMENT OF VEGETABLE ORGANISATION. 269 
present the appearance of a series of circles, or if subjected to a certain 
de gree of equable pressure, they will form a kind of net work, penta¬ 
gonal, hexagonal, or otherwise, according to the presence of various 
modifying circumstances. 
In thus regarding the arrangement of the ultimate vesicles of the 
vegetable organisation to form the cellular structure of plants, we must 
not confine our attention to the mere mechanical principles of juxta¬ 
position and pressure. Each organic vesicle, in a state of activity, 
is endowed, either in itself, or as appertaining to the vegetable structure 
of which it forms a part, with the principle of life. It may, therefore, 
increase in substance and expand in size ; and from this gradual 
expansion or growth, certain changes in its development and in its 
apparent structure will necessarily take place. Thus, by the gradual 
expansion of a simple vesicle, it will attain to a larger size, its shape 
may become elongated or depressed, according to the circumstances 
of pressure under which the expansion takes place, the outer filmy 
covering or envelope may increase in thickness, and the secondary 
vesicles of which this film consists become so far developed as to be 
sensible to our modes of investigation,—and lastly, the organic molecule 
may acquire the property of reproduction [[division]] and by the forma¬ 
tion [inflation]] of other vesicles from the inner [[or outer]} surface of its 
filmy covering, or, more probably, by the development of the pre¬ 
existing particles of which this covering is composed, the vesicle, which 
was either simple, or to our senses apparently so, becomes compound, 
having its central [or exterior]] portion occupied by other and secondary 
vesicles. That these are not merely speculations, has been fully 
established by the researches of M. Raspail upon the minute chemistry 
of organic products*. In examining the granules, or vesicles of 
fecula, a vegetable product of great importance, and of which the seeds 
and roots of many plants almost entirely consist, he observed that, 
subjected to a limited artificial heat, the membrane, or filmy envelope 
constituting their external coating was capable of gradual extension, 
the granules increasing in size, and that at the same time globules were 
formed all over its surface, resembling new grains of fecula, attached by 
a liilum or minute scar to a membrane. “ Analogy,” observes M. 
Raspail, “ seems to point out before-liand that, under the influence of 
natural causes which affect vegetation, whose action, though slow, is 
durable, this development should possess a more regular character than 
under the influence of an artificial cause. What is thus indicated by 
* And by a F.L.S. in a paper read at one of the meetings, on the development of an 
Agamous plant, which the writer observed for several days, and remarked that the new cells 
rose consecutively from the points or edges of the old ones.—E d. 
