Electric Lights for Photo-micrography. 8038 
maining unaltered, the distance was increased so as to give 66 
diameters, It will be understood at once, that on account of 
the increase of distance, the second picture would have been 
slightly less sharp than the first, and the third than the second, 
had precisely the same source of light been employed; never- 
theless, in spite of this disadvantage, to which they were pur 
posely exposed, the magnesium and electric pictures are far 
superior to that taken by sunlight, and of the two the electric 
is much the best. It is especially to be observed, that in the 
electric picture the contrast obtained is so great that the objects 
appear clearly defined on an almost perfectly white ground, 
which is never the case with photo-micrographs taken with the 
sun as a source of illumination. 
As a further illustration of the capabilities of the magnesium 
and electric lights, I add a few photographs taken by each. 
By THe Maenesium Lieut. 
Arachnoidiscus Ehrenbergit. Magnified 400 diameters, by 
Wales’ 1th. Negative 114 (new series.) 
Small vein and capillaries, from the muscular coat of the uri- 
nary bladder of the frog. Magnified 400 diameters, by Wales’ 
rth. Negative 103 (new series). ‘This negative is taken from 
yi perekion No. 3378, Microscopical Series, in which the blad- 
t was injected with a half per cent solution of nitrate of silver, 
and subsequently stained with carmine dissolved in borax. 
The pean was then brushed off with a camel’s hair pencil, 
and the preparation transferred through absolute alcohol to 
ss balsam; the photograph reproduces every thing but the 
color. 
By THe Execrric LicHt. 
Pleurostaurum acutum. Magnified 340 diameters, by Wales’ 
ith. Negative 109 (new aes) : 
Triceratium favus. Magnified 340 diameters, by Wales’ ;th. 
Negative 110 (new series). 
Navicula spima. Magnified 840 diameters, by P owell and 
Lealand’s immersion ;;th. Negative 112 (new series). 
Human red blood corpuscles. Magnified 1,000 
Powell and Lealand’s immersion th. Negative 145 (new series). 
tion of an epithelial cancer of the larynx. mified 400 
i es). This 
hegative is taken from preparation No. 2277, Microscopical — 
eon. i print shows the 
th great distinctness. : 
ammatophora marina. Magnified 2,500 diameters, by Powell 
and Lealand’s immersion ;;th. Negative 161 (new series). 
4 
es of the hs here referred to, sent us by Dr. 
A Sarai Hage a and beauty any specimens of 
photo-micrography we have seen.—Ebs. ] 
