1908. | Minute Structure of the Nervous System. 431 
illustrated by elucidating figures, entitled: “Das leitende Element des 
Nervensystems und seine topographischen Beziehungen zu den Zellen” 
(1897). By the help of a new gold-staining method he had succeeded in 
showing in the ganglion cells of 
certain worms, and especially 
finely in the unipolar cells of the 
Hirudines (fig. 10), an intra- 
cellular reticulum of fibrils which 
form a continuous network round 
the nucleus and also near the cell 
surface ; from that network there 
proceeds through the single pro- 
cess an unbranched fibril which 
extends into the Punktsubstanz. 
In the vertebrata, too, Apathy 
had found fibril network in the 
ganglion cells; this he described, 
but did not illustrate by figures. 
In conjunction with this dis- 
covery of the neurofibrils, excel- 
lent in itself, Apathy built up a 
whole hypothetical theory regard- 
ing the minute structure of the 
nervous system. Of that theory 
it is not easy to give a brief 
summary, but these are the chief 
points in it:—The neurofibrils dis- 
covered by him form the specific 
constituent of the nervous system, 
the nervous portion proper, the 
conducting element; they are 
independent structural parts ; in 
the nerve-fibres they preserve 
their individuality; in three 
places, however, they form reti- 
cula, viz.,in the ganglion cells, in 
Fig. 10.—Two Unipolar Nerve-cells from a Gan- 
glion of the Ventral Nervous Chain of 
Hirudo. In the cells is seen the fibrillar net- 
work of Apathy, running down through the 
cell process into the Punktsubstanz, which 
consists of fine twisted fibres. 
the terminal organ (the sensory cells, etc.), and in Leydig’s Punktsubstanz, 
in which they subdivide into an exceedingly intricate reticulum, Apdathy’s 
“ Klementargitter,” in which the sensory nerve-fibres in particular dissolve 
and lose their individuality. 
Jowe 2 
