Busk on Starch- Granules. 
65 
lies in the other half, a watch-glass shaped basin is formed, 
which after boiling and pressure between the two glasses, 
appears, in consequence of the delicacy and elasticity of the 
membrane, as a flat, round-edged disc." 
According to him, it follows, that the starch-granule, in its 
more usual form at least, is formed by the inrolling upon itself 
of this spherical or ovate vesicle. It is not very easy, at all 
events I do not find it so, to comprehend M. Martin's expla- 
nation of the mode in which this inrolling or involution takes 
place, nor have my own observations as yet enabled me to 
express a very decided opinion with respect to this point. 
The appearances exhibited in the microscope, under the action 
of strong sulphuric acid, convey the idea rather of an unfolding 
of plaits or rugae, which have, as it were, in some kinds of 
starch (those with a long fissure - like or stellate hilum 
especially) been tucked in towards the centre of the starch 
grain, than of the unwinding of rolls. And I conceive that 
the apparent laminae are nothing more than the indications of 
the edges of such plicae or folds in the contracted state, upon 
which I shall say a few words presently. The starch-grain 
of the horse-chestnut perhaps affords as good an example as 
any, and one readily obtainable, of the appearances which 
might be supposed to arise were the constitution of the granule 
such as I have just described ; that is, as far as the tucking in of 
the vesicle towards the centre is concerned, because in this grain 
I am not aware that the concentrically laminated appearance 
arising from folds of the vesicle is evident. Fig. 10, PI. VIII., 
represents the usual forms and aspect of the unaltered starch 
of this fruit, and figs. 11, 12, 13, various granules in different 
stages of evolution under the use of strong sulphuric acid. 
If it be allowed that the starch-vesicle, as the ultimate 
product of the evolution of the grain might perhaps be 
termed, be elastic — which, in all probability, it is — it is 
easy to understand, as in fact is pointed out by M. Martin, 
that the portions which are folded into the interior must be 
more or less compressed, and thence denser ; in consequence 
of which inequality of tension the phenomena exhibited 
under polarised light might be explained. I have examined 
several varieties of starch, such, for instance, as of the Po- 
tato ; the Arrow-root termed " Tons les mois," which is, t 
believe, afforded by a species of Canna ; two other kinds of 
arrow-root ; the starch of the Spanish Chestnut ; of the Yam ; 
of a species of Curcuma^ which seems to be identical with East 
Indian arrow-root ; of Cycas circinalis ; Zamia integrifoUa ; 
Arum maculatum^ and what is termed Tacca arrow-root ; and 
find more or less distinctly in all, indications of a similar 
