30 
G. H. Parker 
the retina or spreading over the face of the corneal cuticula. The 
preparation was then ìnverted over a small glass box containing 
enough water to bathe its convex surface, and the whole appa- 
ratus was placed under the microscope so that the cut surface of 
the preparation could be inspected. In preparations that had been 
carefully made, the ommatidia were found stili regularly arranged 
as in life, and, since the front face of the eye was bathed in water 
and the retina was permeated with normal fluids, and, further, since 
ali the refracting surfaces artificially introduced were rendered in- 
effective by being at right angles to the light, it was assumed that 
the requirements for exact Observation were complied with. Since 
it was necessary to make the preparations in the light, the experi- 
ments were conducted on eyes in which the pigment had taken the 
Position characteristic for a retina brightly illuminated. 
The results obtained were brietly the following. Light never 
penetrated the eye to the depth of the basenient membrane ; for this 
always appeared uniformly black, even when the front face of the 
retina was illuminated with sunlight reflected from a piane mirror or 
with the rays from a streng electric arc-light. This Observation, if 
correct, seems to me, as previ ously stated, to render Lowne's theory 
untenable. When the preparation was made so that the proximal ends 
of the rhabdomes were exposed and the retina was illuminated with 
streng sunlight or light from an electric lamp, the rhabdomes ap- 
peared as small irregulär pinkish areas, but the light which they con- 
tained was so faint that the presence or absence of an image in 
them could not be satisfactorily determined. When the preparation 
was made so that the distai ends of the rhabdomes were exposed, these 
bodies appeared, even when illuminated with dififused daylight, as 
small pinkish areas set in an opaque black üeld. Each rhabdome 
was uniformly bright and presented not the least indication of an 
image within its area. When a lamp was used and the amount of 
light given out by it was made to vary, these variations, even when 
very slight, were observable in the rhabdome. When an opaque 
object, such as a peucil, was held in the light between the lamp 
and microscope, its position was marked by the darkening of certain 
rhabdomes, and, when it was moved to and fro, the order of succes- 
sion in which the rhabdomes became dark showed conclusively that 
it was represented in the retina as a whole by a single erect image. 
In preparations that were made for a level slightly beyond the 
distai ends of the retinulae and that showed, consequently, only the 
