492 EDGAR J. ALLEN. 
fibres start and in which sensory fibres end, namely, the two 
commissural ganglia and the gastric ganglion. The two com- 
missural ganglia are in communication with the central 
nervous system by means of fibres which enter it from the 
commissures, and have also a special direct communication 
with the brain by means of fibres which pass through the an- 
terior median nerve, and bifurcate in the cesophageal ganglion 
(figs. 1, 8, oH). The gastric ganglion is placed in common 
communication with both commissural ganglia by means of 
elements originating in cells in the cesophageal ganglion, the 
processes of which divide into three main branches (D). It is 
also placed in independent communication with each commis- 
sural ganglion by means of elements originating in cells of the 
latter, and running through the esophageal ganglion. 
III. 
I propose to add here a few remarks upon the varicose or 
beaded appearance so often presented by nerve-fibres in pre- 
parations made by the methylene blue method, or by the 
method of Golgi, and on the swellings which occur on the 
finer nerve-endings. These contain the conclusions arrived at 
from observations on the adult Astacus, on embryonic lobsters, 
and on the larve of Palemon and Palemonetes. 
In the two cesophageal commissures of Astacus in fig. 1, I 
have inserted numerous typical beaded fibres, which illustrate 
the great variety of appearances presented. In some cases the 
beads are almost spherical and are joined together by long, 
thin threads; in others they are elongated spindles, joined by 
shorter threads, whilst in yet other cases they form long 
cylinders with pointed ends, the individual ones hanging to- 
gether by the points. 
Figs. 8, 9, 10, and 11 are drawn on a larger scale from pre- 
parations stained with methylene blue and fixed with ammo- 
nium picrate. 
Fig. 8 represents a fibre in which many of the beads are 
