158 
Beraarks on the 
[Monthly Microscopical 
Journal. Sept. 1, 1869. 
in many cases. Immediately outside this are three layers of large 
cells with protoplasm and large nuclei. Surrounding this layer is 
a single series of small cells placed very close together, containing 
a densely granular protoplasm, and very large, often two, nuclei, 
probably a cambium layer. External to this is a layer of epidermal 
cells, not apparently thickened, the whole being enclosed by what 
appears to be a thickened cuticle. Parts of the young radicle are 
covered with hairs. These could be very clearly seen, and their 
mode of formation observed. I cannot detect any thickened cuticle 
at those parts where the hairs are developing. The hairs are direct 
prolongations of the epidermal cells, and in general the contents 
and nucleus can be seen to have been carried forward, and occupying 
the centre of the hair. The sections I have now before me, show- 
ing the hairs, are much farther from the growing point than that 
described above as having a thickened cuticle, but no cuticle is 
visible. The hairs elongate very much, without dividing; the 
nucleus in most was wanting, although the granular contents re- 
mained. Here and there large spaces filled with cell-sap were seen, 
and in one instance the contents of one of these long cells were 
seen oscillating backwards and forwards for some time. The use of 
the staining process does not seem to be attended with any great 
difficulty, and, I have no doubt, important results may be obtained 
by careful study of its action on germinating plants. — Transactions 
of the Botanical Society of Edinburgh : pa^er forwarded hy the 
author. 
yi. — Some Further Bemarhs on an Illumination for Verifying 
the Structure of Diatoms and other Minute Objects. 
By F. H. Wenham. 
Additional observations with the principle oi illumination, sug- 
gested in this Journal for July last. No. VII., have shown that it 
displays many objects with a degree of truth not obtainable by any 
other means ; for it must be borne in mind that it involves this 
singular peculiarity, viz. the whole of the light is conveyed into 
the interior of the object itself, which appears self-luminous in a 
jet-black field. In all other methods with which we are acquainted, 
light is either directly transmitted, or thrown on the surface, the 
glare from which in many instances prevents the interior structure 
from being seen. 
The cut is an arrangement illustrative of this principle of illu- 
mination, a is a right-angled prism, or which may be a hemi- 
spherical lens, as shown by the dotted lines ; b is a condensing-lens, 
behind which, and also below the prism, are stops c and d; e is 
