114 
ME. J. W. HULKE ON THE ANATOMY OF THE 
nations of the optic nerve-fibres; and at their junction with the outer segment the con 
version of light into nerve-force may take place. 
4. The outer granules being the nuclei of the inner cone- and rod-segments, probably 
maintain the integrity of these as living tissues, and are not directly concerned in their 
specific functions as organs of perception. 
5. The primitive bacillary fibres are the link by which the cones and rods communicate 
through the inner granules and ganglion-cells with the optic nerve-fibres. 
6. The smaller inner granules are nuclei of the oblique bacillary fibres in the inner 
granule-layer ; or they may be small bipolar ganglion-cells, and act specifically on the 
forces transmitted through the oblique fibres from the cones and rods. The larger inner 
granules not being distinguishable by any definite structural characters from the smaller 
cells of the ganglionic layer, may agree with these latter cells in function. 
7. Since the ganglion-cells (of the ganglionic layer) are fewer than the inner granules, 
and much fewer than the cones and rods, and since it is probable that these latter com- 
municate with the optic nerve-fibres only through the ganglion-cells, it follows that one 
ganglion-cell probably is in correspondence with more than one inner granule and with 
several cones and rods. From this it is not an improbable conjecture that the cones and 
rods are disposed in groups*, each of which is represented by one or more ganglion- 
cells, the function of which is to connect or coordinate the individual action of the 
separate bacillary elements in their groups in a manner analogous to that attributed to 
the ganglion-cells of the spinal cord by V. der Kolk. 
8. There is a close general resemblance between the human fovea and that of the 
chameleon f. 
Description of the Plate. 
PLATE VII. 
Fig. 1. A vertical section through the centre of the fovea centralis in the vertical meri- 
ridian, extending about halfway towards the periphery of the macula lutea, 
X 240. 
1. Bacillary layer. 
2. Outer granule-layer. 
3. Cone-fibre plexus. 
4. A granular band between the latter and the inner granule-layer. 
5. Inner granule-layer. 
6. Granular layer. 
7. Ganglionic layer. 
a. Centre of fovea ; b, membrana limitans externa ; c, membrana limitans 
interna ; d , section of a blood-vessel. 
* I have an impression that I have seen this in a German author, but have not been able to find the passage 
again. 
f H. Mulleb, “Ueber das Auge des Chamaleons,” 'Wurzb. Naturw. Zchr. Bd. iii. S. 36. 
