II4 THE MICROSCOPICAL NEWS. 
crombie, Wilson, and Redmayne, and of Messrs. Wenham and 
Shadbolt, have for long been connected with a successful pursuit 
of the art. A specimen of the work of Dr. Maddox, of London, 
who photographed the objects delineated in the frontispiece of Dr. 
Beale’s work on the microscope, now lies on the table. Mr. York 
has also just published a series of transparencies of micro objects 
suitable for lecture illustration. 
I have also prints of diatoms from negatives taken by Fritsch 
and Miller, of Germany, and published by Williams and Norgate, 
14, Henrietta-street, Covent Garden, London. One of the prints 
is a magnified representation of the set of diatoms so marvellously 
prepared by Moller, of Schleswig-Holstein, and known as the 
“typen-platte,” or type plate. It contains 100 specimens of these 
beautiful organisms, which are now classed under the: vegetable 
kingdom, and are found both in a fresh and fossil state over the 
whole world ; for any stagnant pond, running ditch, or seaside pool 
will afford living examples for the microscopist. 
I diverge for a moment from the immediate subject of my paper 
to describe these peculiar organisms on account of the beautiful 
skeletons they contain, which form favourite subjects for the photo- 
micrographer, the valves presenting a flat plane to the focussing- 
screen, and exhibiting wonderful variety in the sculptured markings 
on their faces. As a rule they consist of two plates of siliceous 
material covered with delicate patterns, the plates being held 
together by a band or hoop of similar material, the whole forming 
a sort of flat case—in some specimens like a round, shallow snuff- 
box, and containing protoplasm within. For microscopic purposes 
the specimens are boiled in acid, and the clean shells mounted 
dry or in balsam. 
These examples of the German photographers, however, do not 
in any way exceed in beauty the work privately published by my 
late lamented friend, Dr. Redmayne, of Bolton, whose book of 
diatom photographs is also here for inspection. 
Dr. Woodward, of Washington, has kindly sent me for the pur- 
pose of this paper a print of the diatom, Surirella gemma, as an 
example of high magnification and the resolution of difficult 
markings. Few microscopists, comparatively, succeed with their 
own instruments in resolving the lines of dots thereon, even with 
high powers, their resolution being much more difficult than that of 
the common test object Pleurosigma angulatum, to which I have 
before referred. This photograph was taken with a lens of =; focus, 
made by Powell and Lealand, and the magnification is 2,800 
diameters, the dots, so plainly seen, each measuring about g7i55 
of an inch; but I cannot say whether the negative was afterwards 
enlarged. 
Those interested in this subject may find magnificent specimens 
