BRANCHIAL NERVE ROOTS. 



77 



constitutes the posterior lateral portion of the core of the pedal ganglion. (Fig. 63). 

 A small group of fibers extends beyond the main core into the median neural 

 region of the neuromere. (Figs. 60 and 61, n.p.) This neuropile center is very 

 dense and stains with great intensity in von Rath's preparations. 



The haemal fascicle consists of small nerve tubes with sharply defined axis 

 cylinders, separated by a wide, clear space from the outer sheath. They are 

 motor fibers arising from the pecuhar haemal neuromeres, H"^'^ (Fig. 62, m.t.) 

 They supply the branchial muscles. 



Fig. 6z. — Anterior branchial neuromere of a young Limulus, showing the course of the principal neurones. 



surface; methylene-blue preparation. 



Neural 



The oval mass of neuropile in the ganglion of the branchial nerve consists of 

 an extraordinarily complex system of interwoven bundles of very fine fibrils. In 

 this neuropile the following fibers terminate : i . the dendrites of about three- 

 quarters of all the fibers of the branchial nerve: these fibers are sensory. 2. 

 the collaterals of the motor neurones, H^'^. 3. the collaterals of the E neurones 

 whose axones cross in the posterior neural commissure, and 4. the dendrites of the 

 minute C neurones that constitute the principal cellular covering of the ganglion. 



