gniomalonist 
uw ” Beg, 
JOURNAL or VARIATION. 
Von. XE. ~Now-11. November 15x, 1900. 
AND 
Photographing the eggs of Lepidoptera (with plate). 
By F. NOAD CLARK. 
The illustrations of lepidopterous ova exhibited in Plate XI have 
been reproduced from photographs made with the microscope from 
freshly-laid specimens, kindly supplied me by Messrs. Prideaux, 
Montgomery, Tutt, and Dr. Chapman, to whom I am much indebted, 
Those of the Lycenids lend themselves admirably to photography, 
in that they are of small size, and the surface markings are more 
or less in one plane of focus. The spherical surface of the larger 
ova renders photography more difficult, and in some cases, such as the 
Argynnids and larger moths, almost impossible. 
Under casual observation, the several species of Lyceenids appear 
to present but little difference from each other, but careful examination 
will show that really marked differences exist in most of the species. 
This is especially noticeable between those of Polyommatus icarus and 
P. bellaryus, Nomiades seniargus, Callophrys rubt, &e. 
The method of photographing these eggs is ‘comparatively simple. 
The ultimate result is much enhanced if. the ova are mounted in a 
suitable manner; for instance—a white ege should have a dark back- 
eround, and vice versd. Whenever possible, the egg should be photo- 
eraphed in situ, that is, as laid in the natural state, either on leaf, bud, 
or flower calyx, &c. In some of the examples illustrated they have 
been detached from their natural support, and, for the sake of contrast, 
placed on a spot of asphalt varnish. It is absolutely necessary that the 
eges should be photographed in a plane exactly at right angles to the 
axis of the microscope, otherwise some of the eges Gf ina group) will 
certainly be out of focus, and consequently blurred in outline. 
The objective I use is a 2-inch, and I make it an invariable rule to 
photograph all ova at precisely the same magnification, so that the 
results will give a correct idea of their relative size. Thus, the eee of 
Cupido minima is seen to be the smallest of the genus in actual size, as 
its name implies. Illumination is effected by means of an ordinary 
bull’s-eye condenser, focussing obliquely the light from a good paraffin 
lamp. Exposure of the plate varies from one-half to two minutes. 
Until a lens is invented which will give an image of a spherical 
object, representing more than one plane of focus, we shall have to be 
content with the present capabilities of micro- objectiv es. The obtaining 
of this, I fear, is far distant, but at any rate photo-micrography in its 
present state of perfection, gives us a correct and satisfactory means of 
