244 PHYSIOLOGICAL BOTANY. 



the object holder, which is not usually the case, for in 

 other plants the granules retain their connexion. The 

 author then passes to the investigation of how these 

 granules of starch are formed and developed. We might 

 at first imagine, says he, that as in crystallization, the 

 amylaceous plasma (the analogue of the saline solution) 

 is deposited upon the little globules which first separate, 

 and that in this manner, by the continuation of depo- 

 sition upon their outer surface, larger granules are formed. 

 We might add to the author's explanation that the 

 granules are formed around a nucleus, as is usually con- 

 sidered to be the case from the manner in which crystals 

 are formed. According to the author's view, the twin 

 granules of the nucleus of the one individual must lie 

 close beside the nucleus of the other individual, and 

 nearly in that plane in which both are connected, or 

 near the parchment of the kettledrum, if the above 

 comparison is retained. This is not the case, for the 

 nucleus is situated in the bottom of the kettledrum, at 

 the end of the elliptical or spheroidal section (this is 

 also shown by the figures given by Bischoff.) The 

 author then proceeds to the question whether the pres- 

 sure of x the cell inclosing them might not produce an 

 angular form. But this is not the case, for the granules 

 have an angular form, even when they do not completely 

 fill the cells. It is evident, says the author, from what 

 we have stated, that pressure cannot be the cause of the 

 formation of the gland-like collection of starch. From 

 all this, he adds, all that remains is the prospect of a 

 peculiar formative process in the vegetable kingdom. Re- 

 garding the vegetable cell, we know with perfect certainty 

 that the concentric appearances, as seen e. g. in the stony 

 tissue, as it is called, of the pear, &c. arise solely from 

 the centripetal formation of layers. But nothing is op- 

 posed to the view that the layers of the granules of starch 

 also are formed by centripetal, i. e. internal deposition ; on 

 the other hand, this hypothesis is supported by the fact 

 that the nucleus, as it is called, of Fritzsche, or the central 

 cavity of Schleiden, contains much water, and is, as it 



