482 EDGAR J. ALLEN. 
Posterior nerve-root. Azé. 17. Ganglion of Antenna II. 7h. J—X. Thoracic 
ganglia. J—VJ. Form anterior ganglion of adult. H#—. Elements, chiefly 
motor. See pp. 495—499. Somewhat diagrammatic. 
Fig. 2.—Brain and thoracic ganglia of Homarus embryo. A. Elements. 
Fibres run from cell in anterior ganglion, and pass down ganglionic cord . 
For individual elements see pp. 488—491. 
Fic. 3.—Ditto, B elements. Fibres run from cell in ganglion forwards to 
brain (see pp. 491—493). 
Fic. 4.—Ditto, C and D elements. OC. Fibres run from cell backwards 
and end in next ganglion. JD. Fibres run from cell forwards and end in next 
ganglion but one. E. Motor element. (See pp. 493, 494). 
Fie. 5.—Branching of giant fibres in sixth abdominal ganglion. A (a) Br. 
Giant fibre. 
Fic. 6.—View of brain of Homarus embryo from the ventral surface. 
A (a) Br. Cell in which giant fibre originates. 
Fic. 7.—Element C. Camera drawing from fresh preparation. Late em- 
bryo. xX 250. 
Fic. 8.—Posterior thoracic ganglia (Th. VI—Th. XI) of Homarus 
embryo. Elements C and D stained. Camera drawing from preparation 
fixed in ammonium picrate. x 100. 
Fic. 9.—Posterior thoracic ganglion (Th. XI), showing nerve-cell (~. c.) and 
fibre going to muscle (musc.). Camera drawing from preparation fixed in 
ammonium picrate. 250. 
Fic. 10.—Sensory cells in ectoderm of dorsal surface of abdomen of 
Homarus embryo. 
Fic. 11.—Three abdominal ganglia (Abd. II—IV) of Homarus embryo, 
showing sensory elements M. 
Fic. 12.—A. Second abdominal ganglion (Abd. II) of Homarus embryo 
showing bifurcation of fibre of sensory element M. JB. Ditto, at a later 
stage of staining. 
Fic. 13.—Nerve-ending in Th. I. 
