40 PHOTO-MICROGRAPHS. 
referred to is reduced to aminimum, and the writer 
has succeeded in making some very fair photo- 
graphs from objects of this kind. Fig. 2, Plate 
IX., has been introduced as an illustration of what 
may be done in this way. It also illustrates the 
difficulty of securing uniform illumination, and of 
obtaining a field in which the definition is good 
throughout. We have the same difficulty with 
these minute stellate hairs on the leaf of Deulzia 
scabra that the portrait photographer has with the 
nose and ears of his subject. It is difficult to do 
justice to both. 
The definition, also, is not as perfect as could 
be desired, although the objective used is one of 
the best in my collection (Tolles’s two-inch). 
Another photograph by the same lens is given in 
Fig. 1, Plate VU. The general effect is very good, 
and we recognize the fact that these pollen grains 
are little spheres; but the minute spines which 
project in all directions from their surface can be 
seen only at the outer margin of the hemisphere 
facing us. These correspond with the ears of 
our man; and as the amplification is twenty-five 
diameters, the spines corresponding with the nose 
are as much out of focus as this organ would 
be in the face of a man magnified twenty-five 
times. 
In my experiments with reflected light, illumi- 
nation has been effected by means of a Lieberkihn, 
by which parallel rays reflected from the sky are 
concentrated upon the object. When the amplifi- 
cation is as much as twenty-five diameters, it is 
