41 
G. H. Parker 
It is interesting to observe (cf. Fig. 49) that Ihe body of these large 
fibres seems to pass over directly and almost entirely into their 
fibrillations and that the ganglionic cell is attached to the fibre by 
a relatively delicate process. This condition rather favors the idea 
that the ganglionic cell do es not participate directly in the nervous 
functions and that the latter have their seats in the fibre and the 
»Punktsubstanz«. 
By way of summary, it may be Said that the fibres of the distal 
decussation begin in the first ganglion and terminate in the second 
one and with their attached ganglionic cells constitute a series of 
neurons that, from their relation with those connecting the retina 
and first ganglion, may be called the neurons of the second order. 
Second Optic Ganglion. The mass of »Punktsubstanz« that 
forms the centro of the second ganglion is much thicker than that 
in the first ganglion; it is slightly convex distally and concave 
proximally and usually rests in a position somewhat oblique to the 
axis of the optic stalk, its anterior edge being proximal to its pos- 
terior one (PI. 1 Fig. 27, II). In structure it is much simpler than 
the »Punktsubstanz« of the first ganglion. It is not surrounded by 
anythiug that can be called a neuroglia and its substance is not 
divided into neurommatidia. It cousists, in fact, of a rather uniformly 
matted mass of fibrillae derived from the two sets of nerve fibres 
in connection with it and surrounded laterally by ganglionic cells 
(PL 1 Fig. 35). 
Second Decussation. The nerve fibres that emerge from 
the proximal side of the second ganglion decussate in their passage 
to the third ganglion in almost exactly the same way as do those 
in the first decussation. Even the plane in which this crossing 
occurs, the anteroposterior, is the same in the two cases. Each fibre, 
so far as my observations go, is connected with a ganglionic cell 
usually of the small type and the layer formed by these cells sur- 
rounds the »Punktsubstanz« of the third ganglion in the character- 
istic horseshoe pattern (PI. 1 Fig. 36, cl. gn). All these fibres begin 
in the fibrillar material of the second ganglion and almost all of them 
end by breaking up into fibrillae in the third ganglion; a few, 
however, pass proximally beyond this ganglion. In preparations 
stained with raethylen blue, it is not uncommon to find one or two 
large fibres (cf. PI. 3 Fig. 59, green) extending from the anterior end 
of the second ganglion to the posterior end of the third, where they 
each are unitcd with a ganglion cell, in this instance of the large 
