SELECTION, ETC, OF OBJECTS FOR PHOTOGRAPHING. 117 
up a single plate, as in the present volume, these 
should have as nearly as possible the same tone 
printing quality; and they will require to be skil- 
fully cut for the purpose. 
Diatoms should betmounted in balsam for pho- 
tography, and the amateur will do well to obtain 
a slide of arranged diatoms by a skilled prepara- 
tor. The slides made by J. D. Méller, of Wedel, 
in Holstein, are celebrated for their beauty and 
perfection. Plate XII., in the present volume, 
is from the fourth square of the Typen-Platte of 
this Prdparator. 
INSECTS. 
Small insects, which are not too deeply colored, 
mounted in balsam, are very good objects to pho- 
tograph with low powers. The wings, tracheal 
tubes, feet, antenne, etc., may also be photographed 
with higher powers. The proboscis of the blow- 
fly is a favorite subject. 
The suggestion has already been made that 
photo-micrographs of the larger insects might be 
made by reflected light with a lens of compara- 
tively long focus but good defining power, and 
that the enlargement might be made from the 
first negative, in which the image should be even 
less than the natural size of the object. 
ILLUSTRATIONS OF ANIMAL HistoLoGy AND PATHOLOGY. 
The beautiful photo-micrographs of histological 
and pathological preparations by Dr. Woodward, 
made at the Army Medical Museum, show what 
