148 PATTEN. [Vot. II. 
longation is filled with dark granular protoplasm. Beyond the 
bend it is reduced to a coarse, colorless, and refractive fibre that 
may be followed outward into the eye. As development goes 
on, the bend of the fibre is carried more and more into the optic 
ganglion until it reaches the medulla, where it becomes hyaline 
and refractive and breaks up into a tuft of a dozen or more 
fibrille that extend along the sides of the medulla and then 
turning inward, disappear (Fig. 48). 
The outer end of the cell is somewhat flattened, and on either 
side is continued into a tube-like prolongation with clear, homo- 
geneous contents. In the centre of the tube, I have seen on 
several occasions what appeared to be a small fibre, but cannot 
say positively that it was such. The protoplasm of the cell pro- 
trudes a little near the mouth of the tube, but is not continued 
into it. 
These tubes, or fibres, are difficult to follow, and I have only 
succeeded in doing so in a few cases, and then not very far. 
They extend, at right angles to the great inner stalk, in opposite 
directions along the under surface of the neurilemma, and I 
should judge they served to connect the ganglion-cells with one 
another. I see no reason to suppose they extend into the 
medulle; they do not run in that direction, and no fibres were 
seen running into the medullz that could not be referred to the 
stalk-like prolongations of the ganglion-cells. 
The gigantic ganglion-cells continue to divide, but with 
decreasing frequency, up to about the time of hatching. At 
that period, there is usually but one cell of enormous dimensions 
on the side of each medulla. Their position, size, and shape, as 
shown in Fig. 48, are very constant. In rare cases, there may 
be in the larve two large cells side by side, one a little smaller 
than the other. In the full-grown larve, the cells are propor- 
tionally smaller and less conspicuous. 
In Fig. 48 is shown a pair of ganglion-cells placed end to end, 
and easily distinguishable from the surrounding ones by their 
peculiar shape. There was an exactly similar pair in the optic 
ganglion on the other side of the head, and I have also seen them 
in one or two other cases, so that I do not doubt that they are 
usually present during these stages. 
There is a singular modification of the sixth gigantic ganglion- 
cell, in that its inward prolongation is divided into two branches, 
