REPORT ON THE AMPHIPODA. 489 



the periphery of the oesophagus, partly in the maxillT, in which in point of form and 

 structure they repeat the leg-glands. 



5. The function of these glands is the preparation of the ferment (Enzyme), which is mixed 



with the food at its entrance into the cesophagus, to facilitate the digestion of starch and 

 albuminoid substances. 



6. The alimentary canal (Darmcanal) is devoid of every form of gland-cells. To the muscular 



cesophagus of complicated structure, lined with chitinous Intima, succeeds the ccsophageal 

 stomach (Schlundmagen, Vormagen), with two caaca (Nebentaschen), stretching into the 

 crop (Magendarm). In this digestion is carried out. The crop which surrounds it, 

 situate in the head and the two first perreon-segments is, like its two forward-directed pairs 

 of so-called liver tubes, lined with a deep cylindrical epithelium, which repeats the structure 

 of the epithelium of the mid-gut (Diinndarm-epithel), and serves for resorption. The 

 narrow intestinal tube (Darmrohr), is lined with a polygonal pavement epithelium, 

 and in the sixth pleon-segment passes over into the short rectum (Afterdarm), which is 

 fastened to the integument by means of dilators. [At page 23, in the Munddarm of 

 Phrcmima three sections are distinguished as Mundlwhle, ScJdundkopf and Sehlundrohr or 

 cesophagus.] 



7. The annular muscles of the intestinal tube correspond to single muscle-cells, the nuclei of 



which follow one another in a median row on the dorsal side of the intestine. 



8. The heart stretches from the boundary of the heai.l to the middle of the sixth peraeon-segment, 



and possesses, besides the three pairs of ostia provided with valves and the two aortas, two 

 pairs of lateral arteries. 



9. Each artery arises over an oblong slit bounded by two side-flaps (Seitenklappen) while at 



the base of each aorta lie two obliquely set ostia with a pair of flaps (valve-opening) to 

 each. 



10. The obliquely transverse mu.5cle-rings of the heart are developed from two lateral rows of cells, 

 between which a dorsal and ventral median-suture remains. 



11. Under the heart, adjoining the ventral wall of the heart, there stretches across through the 

 body-cavity a septum composed of large cell-plates. Besides this there is a second septum 

 which occupies a similar position in regard to the intestine, so that the space of the body is 

 divided into three blood-channels bounded by connective-tissue, and communicating with 

 one another by definite openings. Besides these main channels, which are continued on 

 into the head, there exist a number of more peripheral accessory channels, likewise bounded 

 by connective-tissue, which represent the blood-courses of the regular circulation. 



12. The ventral ganglionic chain contains, excluding the subcesoi^hageal ganglion-mass, nine 



ganglia, of which five belong to the pereeon, four to the pleon. The last peraeon- (thoracal) 

 ganglion, just as the last pleon- (abdominal) ganglion, follows the next preceding ganglion 

 immediately. The last pleon-ganglion has arisen out of the concretion of three ganglia for 

 the fourth, fifth and sixth pleon-segments, these ganglia in the embryo being separate. 

 1 .3. The subcesophageal ganglion-mass corresponds to six ganglionic nuclei, or to seven if we take 

 into account the ganglionic centre belonging to the commissures which provides for the 

 nerves of the second antennae. Besides the nerves of the second antennae also all the 

 maxillary nerves are derived from the oesophageal commissure, to which their place of 

 origin has shifted itself. 



14. The peripheral nerves are rooted, not in the so called " Puuktsubstanz " [Dietl's Mai-/,- 

 substanz, p. 57, inijeloid substance, Packard], but derive their fibres from ganglion-cells partly 

 of the corresponding ganglion — as well crossed as uncrossed fibres— partly of the preceding 

 ganglion, partly from the brain. 



15. The fibre-tracts of the so-called oesophageal commissure which enter the brain pass partly to 

 the ganglion-layers of the same half of the brain, partly in crossed course to those of the 



(ZOOL. CHALL. EXP. — PART LXVII.— 1887.) Xxx 02 



