314 MR. H. A. HURST ON THE 
appearances presented by, more especially, vegetable struc- 
ture, after having undergone prolonged torture by chemical 
agency, are no more to be depended upon than those pre- 
sented by a human being under similar circumstances. 
“The striz, if they were the optical expression of lines 
of separation of concentric layers, would, I submit, show 
strongest when the plane of the focus of the object glass 
coincided with the central plane of the granule; but this 
appears to me not to be the case. On the contrary, the 
strie are only shown when the surface of the granule is 
in focus. Some starch grains do not show striz at all, 
whilst those of the Canna Indica show them only on three 
sides. 
“But a strong argument against the concentric layer 
theory is that the nucleus, where all the supposed layers 
are superimposed one over the other, is actually the most 
transparent part of the granule, instead of being the most 
opaque, which would be the natural consequence of the 
presence of a larger number of layers than those existing 
at the opposite end of the granule. 
«This extreme end, where there can be only one layer, 
is, if there be any difference, the darkest part of the 
granule, as can be verified by inspection. 
“In examining the action of any mineral acid, or of an 
alkali, on starch granules — say the largest —I find the 
following phenomena: 
“ Should the agent be much concentrated, the granule 
bursts at once the moment it is touched by it, and lies on 
the glass slide a flat ovate single membrane, no trace 
being discernible of strize or internal layers. If more 
dilute, a gradual increase of size takes place, one or more 
of the striz becoming strongly marked. The hilum or 
nucleus seems to be an aperture through which the agent 
obtains access to the interior, and from it stellate fissures 
arise, caused apparently by the absorption of the agent 
