230 NUNNELEY, ON THE RETINA. 
large. In some portions of the same retina they also appear 
more plentiful than in others, and in some fish, as the golden 
carp, Cyprinus auratus, the venom fish, and the cod, they ap-. 
pear more distinctly as single bulbous bodies, often two lying 
close together, having each a singleconicalprojecting part; while 
in others, as the whiting, the bulb more commonly appears as 
single at first, with two conical ‘projecting parts, and subse- 
quently to split into two portions. The conical portion very 
closely resembles in character the rods, while the bulbous 
part more nearly approaches the granules. Can they be re- 
garded as rods in the process of development? By water 
they are immediately broken up; by ether much distorted, 
and then destroyed ; by ammonia they are instantly (as are 
the rods) dissolved ; by acetic acid they are also destroyed, and 
only a clear globule left. Chromic acid also acts upon them, 
if strong it distorts them much, if dilute it acts as water; 
acetic acid has a similar action. 
The retina of the turtle, if examined instantly the animal 
is killed (for like all others it changes in few hours), is a very 
interesting sight. The outer surface is composed of conoidal 
rods, in shape very like those of a bird, and lke them 
surmounted by brilliantly coloured globules, partially im- 
bedded in the rods. These rods are of large size with the nar- 
row portion inwards, and between them lie a number of oval 
bodies, which are clearly the bulbs of Bowman. They do not 
reach the outer surface of the retina; they are clear, trans- 
parent bodies, exactly in texture like the conoidal rods, and 
hike them, after the lapse of a short time, or immediately on 
the addition of almost any substance, becoming granular. 
There are also to be seen a great number of ovoid bodies of 
nearly the same size as the bulbs, surmounted by coloured 
globules like the conical rods; whether these are bulbs with 
coloured globules attached, or whether they are altered rods, 
with the inner narrow part detached, I am not able to satisfy 
myself, but I incline to the latter opinion, for they cannot be 
seen tn situ; and certainly in many instances, the conoidal 
rod appears with the outer part swelled out into a granular 
bulb, while the inner part is detached and breaks up into 
small discs and granules before disappearing, but, on the 
other hand, the end of many of the bulbs as they float about 
appears perfect. They carry ruby and canary coloured glo- 
bules of various sizes indifferently. I have never seen two 
globules attached to either one rod or one bulb (as Hannover 
says occurs), but I have often seen a loose coloured globule 
accidentally become attached, or the globules of two neigh- 
bouring bodies so lying as to require great care to distinguish 
