66 
Busk on Starch- Granules. 
structure, differently modified, however, in some respects, in 
each. Upon referring, moreover, to the figures of different 
kinds of starch given in Schleiden's ' Botany,' before quoted, 
a tolerably complete series of development, as it may be 
termed, of different forms of starch, will, I think, be suffi- 
ciently obvious. Fig. 13 of Schleiden, representing starch- 
grains from the rhizome of Anatherum iwarancusa* and fig. 8 
those of Iris pallida, show, as I conceive, the simplest form of 
inversion or folding of the edges of the starch-vesicle. A 
further stage is apparent in fig. 12, the starch of Colchicum 
autumnale ; and a further advance may be traced in fig. 14, 
the starch-granules of Arum maculatum, whence the tran- 
sition to the form presented by the starch of the horse- 
chesnut is sufficiently clear, and from these more or less open 
forms to the complete involution seen in the potato-starch, &c. 
The dissection of the starch-grain may be effected in several 
ways besides those I have noticed, and equally, if not more, 
conveniently. And as the dissection effected in any of these 
modes appears to yield the same result, the latter may be 
regarded perhaps as the more worthy of confidence. 
I have usually selected for my experiments the form of 
arrow-root called " Tous les mois." It is a favourable subject 
for investigation, owing to its large size and regular con- 
formation, as seen in figs. 1, 2, 3, 4, 5. The grains of Tous 
les mois are of various sizes and of different shapes, — some 
oval, some more expanded, with a sort of horn or shoulder on- 
each side, or on one side only. The grains, like those of most 
kinds of starch, are not cylindrical, but flattened, and towards 
one end of each grain is a minute circular spot, the area of 
which appears granular ; and concentric to this spot the 
surface of the grain — or rather one of the flat surfaces only 
and the sides — is marked with delicate concentric rings. 
It is these rings which have been described as indicating 
a laminated structure, and, consequently, corresponding lines 
or planes should be seen, under favourable circumstances, 
passing through the substance. This appearance has actually 
been described as existing by Schleiden and others, but I have 
looked for it in vain, and Mr. Quekett, in his Lectures on 
Histology, describes the markings as superficial. His ex- 
pressions, moreover, would plainly imply that this accurate 
observer entertains an opinion with respect to the structure of 
the starch-grain pretty nearly if not quite identical with that 
advocated in this paper, and that, as I suppose, the lines 
indicate the rugae or folds into which the starch- vesicle is 
* Miinter, however, denies the existence of starch-granules like those 
figured by Schleiden in the rhizome of A. iwarancusa. 
