4G ANATOMY AND PHYSIOLOGY OF 



stance of the grannie remains solid, and is corroded and dissolved 

 layer by layer fi'om without inwards. 



Ohserv. 1. Observation has not yet tanght us anything concerning 

 the development of starch granules. That they are originally small and 

 roundish, is decided, and the laminated structure proves that the increase 

 of size does not depend on the expansion in all directions of the original 

 granule, but on gradual deposition of layers produced successively. As to 

 the order of the succession nothing is known. We may, with Payen and 

 Miinter {^^Bot ^eitmig,'' 1845, 193), conclude, from inner layers being 

 softest and richest in water, that the innermost layer is the youngest; 

 when we follow this hypothesis we must naturally assume that simulta- 

 neously with the deposition of each new layer, or rather of a new central 

 nucleus which is by subsequent growth to be converted into a layer, 

 all the old layers expand, and exhibit an increase of thickness, the more 

 irregular the older they grow, since the eccentricity of the organic centre 

 increases with the size of the granule. Or we may conclude, on the con- 

 trary, with Fritzsche and Schleiden, from the young starch granules being 

 globular, and the mnennost layers of fall-grown granules also possessing 

 a globular form, while the outer layers exhibit an irregular thickness on 

 their different sides, — ^further from two starch granules lying side by side, 

 being sometimes enclosed in a common external layer, — that the outer- 

 most layer is the youngest. 



Ohserv. 2. Most recent researches upon starch indicate that all the 

 layers of the granules are composed of one and the same substance, and 

 that there is no enveloping membrane contrasting with the contents. 

 But the latter is likewise asserted in many hands. Sevei^al German phy- 

 totomists, especially Sprengel, had already regarded the granular struc- 

 tures occurring in cells as vesicles and as the rudiments of cells, but 

 Turpin (^^ Organographie 'oegMah" Mem. du Museum, xiv.) and E-aspail 

 i^^Systeme de la Chimie organique'') were the authors who especially deve- 

 loped and disseminated this theory. Turpin regarded the granular struc- 

 t.ies which occur iaceUs (therefore starch and chlorophyU in particular), 

 comprehended by him under the general name of ghhuline, as vesicles 

 which sprouted from the cell-walls, were attached by an umbilicus (for 

 which he took the hilum of starch granules), and grew into cells by subse- 

 quent enlargement. These views obtained greater diffusion in regard to the 

 starch granule through BaspaH, and much credit was given to his state- 

 ment that it was composed of an outer membrane resisting the action of 

 water, and inner contents soluble in water and consisting of gum. All 

 this has been, very properly, long since forgotten, for all these statements 

 rest upon the most wretched observations ] but the utricular nature of 

 the starch grain has been again defended recently by Nageli {^^Zeitschr. 

 f. wiss. Botr iii., 117, Ray Society's FvMications, 1849, p. 183). Accord- 

 ing to him, the starch grain consists of a membrane and fluid contents ; 

 concentric layers are deposited on the inside of the membrane, as in 

 ligniffing cells, thus tlie cavity of the vesicle is reduced to the smallest 

 possible size, being, however, always filled with fluid. Evidence for these 

 statements is sought for in vain, even in the plants named by Kageli, in 

 which he affirms that he found the outer membrane tolerably thick and 

 uncolourable by iodine; whoUy derived from his imagination is the fco!*- 

 ther statement that the granules rendered angular by mutual pressure. 



