. . however, our answer was correct. We rightly assumedthat as the brain and cesophageal commissures movedforwards and upwards, passing through the positionoccupied by these antennal nerves, the two mightunite, so that we described the nerves for the secondantennae as branching off from the brain commissures,this position agreeing best with the position of thesecond antennae in Apus. On comparing this theoretical scheme for the antennalnerves with Zaddachs drawings, we found, as stated,that the nerve for the first antenna, which has
. . however, our answer was correct. We rightly assumedthat as the brain and cesophageal commissures movedforwards and upwards, passing through the positionoccupied by these antennal nerves, the two mightunite, so that we described the nerves for the secondantennae as branching off from the brain commissures,this position agreeing best with the position of thesecond antennae in Apus. On comparing this theoretical scheme for the antennalnerves with Zaddachs drawings, we found, as stated,that the nerve for the first antenna, which has themore ventral position, branched off from the brain-cesophageal commissure dorsally to the nerve of thesecond antennae which has the more dorsal position,so that, if Zaddachs drawings were correct, a slight 1 Backwards is morphologically correct ; actually the brain movedforwards and upwards. THE APODID^E PART I crossing of the nerves must take place. Our ownexamination of the nervous system quite confirmedthis, as shown in Figs. 19,20, and 21. These figures. FIG. 19.—Diagram to show the derivation of the central nervous system of Apus fromthat of a bent Annelid as in Fig. 18 ; drawn on the assumption that the nervesof the first antennae of the original Annelid branched from the first ventralganglion, i, 2, 3, 4, 5, ganglia of the ist, 2nd, 3rd, 4th, and 5th segments. l>,brain of Annelid ; /3, of Apus ; <PI, cesophageal commissures of Annelid ; <ro, &$,the two cesophageal commissures of Apus derived from cc\ , ai, «o, nerves to theist and 2nd antenna; of the Annelid ; aj, a-), ditto of Apus ; c\, e», nerves to theeyes of the Annelid ; TJI, rj-j, ditto to those of Apus. should be compared with Figs. I and 2, which showthe positions of the antennae. This position of the first antennal nerve tells us,however, nothing definite as to the position of the SECT. V THE NERVOUS SYSTEM 73 ganglion. All we can positively affirm is that, ifthe ganglion was infra-cesophageal i
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherlondo, bookyear1892
