478 EDGAR J. ALLEN. 
branches which arboresce in Th. I and in Th. III. The fibre 
therefore influences three adjacent ganglia. 
I have made numerous observations of certain other nerve- 
endings in the thoracic ganglia, which are very possibly the 
endings of sensory nerve-fibres, but the account which I could 
give of these is at present not sufficiently complete to make it 
worth while describing them here, and I prefer to reserve them 
for future investigation. 
THEORETICAL. 
Without entering into a general discussion, which will be 
more suitable after the investigations have been continued to 
a further stage, I shall now endeavour to draw attention to 
some points of interest in the results described above. 
In the first place, the elements C and D (fig. 4), which form 
what may be termed the short internal connections of the cord, 
will be considered. I am of course aware that there is a pos- 
sibility that this arrangement of fibres is purely embryonic, 
and has not yet reached the active condition. This view, how- 
ever, appears to me to be improbable, firstly on account of the 
fact that there is practically no change in the arrangement 
from quite early embryos, in which the eye-pigment has just 
begun to deposit, to the oldest larvze (about one week) which 
I have been able to examine; and secondly, because the 
elements take up the methylene blue in a way which, according 
to present experience, only active nervous tissue does. 
At the outset, the question arises as to what is the signifi- 
cance of the three tufts of fibres which stand opposite to each 
other at the point where each element ends, and of the lateral 
branches, which both elements give off to the neuropile, where 
they cross. My observations agree entirely with those of 
Retzius, Kélliker, and the majority of recent investigators, in 
the fact that I have never, here or elsewhere, been able to 
observe anastomosis of the fibres of different elements. There 
can, however, be little doubt that the view now commonly 
held that it is by means of the finer branches that the 
nervous energy passes from one element to another is the 
