Dr. Maddox, on Photomicrography. 39 
tnres^ trial was made of it on them, but very many of the 
minute hairs were found to be removed, the surface more or 
less roughened^, and thus injured for the purposes of photo- 
micrography. This^ however, might have been due to some 
error on my part. Unfortunately I am not acquainted with 
any method for preserving the natural appearance of the in- 
ternal organs of insects^ as seen in the " live-box.^' The 
granulation given by the use of chromic acid, bichloride of 
mercury, carbonic acid, &c., interferes too much with the 
definition to be of use in " differentiating the internal 
organs for photomicrography. 
In staining the tissues of entire insects by the carmine 
fluid, we introduce a most unfortunate colour for the photo- 
grapher ; but when the prints from the negatives, or the 
transparent positives for the stereoscope or lantern, are to be 
coloured, this defect is less apparent. 
The process of tissue -staining opens a fresh field for us. 
From my success in obtaining fair negatives from some of Dr. 
Beale^s excellent preparations, I feel convinced photomicro- 
graphy can be made, if required, to furnish assistance to the 
anatomist and physiologist for class instruction. When the 
object and microscope are not used, coloured prints of a 
sutficient or convenient size might be employed to more 
closely explain the enlarged diagrams. In the measurements 
of objects the plan is open to less variation than when trust- 
ing only to the eye- should the objects differ among them- 
selves, the difference, as seen in the print, could be readily 
determined ; the striae in the Diatomacea, the angles of minute 
crystals, the felting quality of wool, the coarseness or fineness 
of vegetable products (as cotton), might claim attention, even 
as relates to their market value. To the draughtsman it will 
furnish a means to correct or supply the copy for the pencil ; 
in this manner it has been employed in the American edition 
of Dr. Draper^s ' Physiology,^ and as direct photograph prints 
in the title-page of Dr. Scalers recent edition of ' How to 
Work with the Microscope.^ Should an easy and permanent 
method of printing from photograph negatives be discovered, 
we may hope for its profitable adoption in the illustration of 
our scientific literature, as refers, at least, to the microscope. 
It is now stated that a plan has been found by which a cor- 
rect image can be printed from a negative or positive on to 
the wood-block. A very small quantity of nitrate of silver is 
used with other substances, and these are sufficient to receive 
and furnish the impression without injury to the texture of 
the wood, or interfering with the ordinary method of wood- 
cutting. 
