STUDIES ON THE NERVOUS SYSTEM OF CRUSTACEA. 33 
Studies on the Nervous System of Crustacea. 
By 
Edgar J. Allen, B.Sc., 
Director of the Plymouth Laboratory of the Marine Biological Association. 
With Plate 4. 
IV. Further Observations on the Nerve Elements of the 
Embryonic Lobster. 
In the first part of these studies! an account was given of 
certain nerve elements which had been demonstrated by the 
action of dilute solutions of methylene blue upon the ganglia 
of the embryonic lobster (Homarus vulgaris). The elements 
then described arose, in most cases, from cells which lay in the 
anterior ganglia of the thorax. In the present paper a number 
of additional elements occurring in these ganglia will be 
noticed, together with those found in the posterior thoracic and 
in the abdominal ganglia. 
The method of investigation has been the same as that 
described in my former communication, the results in this 
case, however, having been obtained principally from embryos 
which were near the point of hatching. Several of the new 
elements differ in essential points from any of those previously 
described, and are of interest in throwing additional light upon 
the manner in which different portions of the central nervous 
system, or different movements of the body, are co-ordinated 
one with another. 
1 This Journal, vol. 36, pt. 4, 1894; a preliminary notice occurs in ‘ Pro- 
ceed. Roy. Soc.,’ vol. lv. 
VOL. 39, PART 1.—NEW SER. C 
