152 Miscellaneous. 
the nerves; this I have been able to confirm. He has, however, 
left us in doubt as to the origin of the nerves; and with regard to 
their terminations his observations are very imperfect, which I at- 
tribute to the inferiority of the microscopes of 1844 as compared 
with those of 1862. 
The central nervous system consists of cells and fibres. The cells 
are very delicate, transparent, round, and filled with granulations, 
and their diameter is from 0:02 to 0:05 mill. ; their little nucleus is 
only 0:006 mill. in diameter. In the living animal I could not 
ascertain their presence ; and I could only see ‘them after placing the 
whole animal in a weak solution of chromic acid. The sheath of 
the central nervous system, discovered by Quatrefages, exists; but 
the nervous fibres, denied by him, also exist; they are very deli- 
cate, straight, and covered with small granulations. 
Besides these two elements, there is a great quantity of capillaries 
in the central nervous system. Quatrefages discovered “ that beyond 
the last inflation the medulla spinalis is produced into a delicate fila- 
ment, which becomes dilated and forms a sort of very distinct am- 
pulla on the level of the extremity of the dorsal chord.” The ob- 
servation is correct ; but the ampulla and the whole of this terminal 
filament are nothing but capillaries, a loop of which forms the 
ampulla. 
The spinal nerves spring from the upper part of the sides of the 
medulla spinalis, as I saw in transverse sections. From this the 
roots start in the form of a comparatively thick trunk. There are 
not two roots; but in the interior of the root we find very delicate 
primitive fibres (cylindraxes), which reach it from different sides. 
The roots are surrounded by a sheath, in which capillaries may be 
detected. After its issue the nervous trunk becomes swelled ; and I 
once succeeded in seeing in this swelling a ganglionic cell with its 
nucleus. It is only behind the swelling that the trunk divides, as 
described by Miiller and Quatrefages. I believe that the swelling 
represents the spinal ganglion of the vertebrata. 
Termination of the Nerves.—Of this, Quatrefages saw two modes: 
in one he saw and depicted a nervous filament, ‘‘ terminating in some 
small ovoid vesicular organs, with proportionally thick walls, which 
are probably muciparous crypts;’’ in the other he saw the nerves 
terminate in transparent homogeneous filaments, which at their very 
extremity ‘‘ spread out to form an irregular cone, cr a small ma- 
milla applied against the inner layer of the integuments.” The 
structures described by Quatrefages exist, but he observed only the 
beginning of the end. The little vesicular organs do not constitute 
a termination, but they are placed in the course of the last ramifica- 
tions of the nerves. There are two kinds of these bodies—large and 
small. It is especially in the upper part of the head that I have 
seen them; in the lower part and in the margin of the fin they are 
much fewer. But these bodies, which at the first glance have the 
form of a nucleated cell, are only loops of the nervous fibre; that 
is to say, the fibre, instead of running straight onwards, turns round 
upon itself. Sometimes the arrangement is repeated, so that the 
