62 
Busk on Starch- Granules. 
M. G uibourt * says that the internal portion of the starch- 
grain breaks up in the form of flocculi, whilst the outer 
portion, the membrane, is lacerable, and occasionally exhibits 
the form of an empty pouch. 
The expansion and alteration in form of the starch-grain, 
under the influence of heat and of sulphuric acid and other 
re-agents, is a fact recognised also by Schleiden and those who 
adopt the view of its solid or homogeneous nature ; it is, in 
fact, so obvious a phenomenon that it could not possibly 
escape observation. They, however, and I believe nearly all 
who have adopted the cellular hypothesis, consider this to be 
owing simply to the expansion of the solid body or vesicle. 
Till very recently, Leeuwenhoeck only appears to have attri- 
buted this increase in size and change of form of the granule, 
not to a mere expansion, but to an opening out of the granule 
on one side, or to its evolution in other words, whence it 
assumes a flattened figure, and of course an increase in 
apparent diameter. Although not, in the precise sense, 
understood by Leeuwenhoeck, I believe that his notion, with 
some correction, represents more nearly the true doctrine of 
the structure of the starch-granule than that of any of his 
successors till a very recent period. 
In the Philosophical Magazine for April last is a paper 
' On the Amylum Grains of the Potato,' by A. G. C. Martin, 
Librarian of the Imperial Polytechnic Institute of Vienna, 
which appears to me to contain the germs at all events of a 
correct doctrine with respect to starch ; and as 1 was led to 
pretty nearly the same conclusions as himself, though from 
experiments of a different kind and instituted for a different 
purpose, I have the more confidence in his results. And as 
the procedure I was led, more accidentally than otherwise, to 
adopt is perfectly easy and simple, this paper may at all 
events serve to incite others to repeat the experiments, and 
thus we may hope that the vexata qucestio of the structure of 
starch may in some degree be set at rest. M. Martin's mode 
of experimenting is nearly as possible the same as that 
adopted by the illustrious Leeuwenhoeck, and his results are 
not in the main very dissimilar. 
As the observed results at which M. Martin and myself have 
arrived in the examination of potato starch appear to coincide 
in every particular, it is obvious that the reasoning applied 
to his is equally applicable to mine. These results have in 
both cases been arrived at by noticing the phenomena which 
take place in the amylum-granule during its expansion, and 
* ' Journal de Pharmacie.' 1846, p. 191. 
