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Fig. i, 2. M. giganteum, n. sp.. (Zeiss CC. Oc. i. Cam.-lue. Osmic acid. Hæmatoxylin.) Two succesive horizontal sections
through the ventral nerve-cord. Fig. i is a more ventral section than fig. 2. In fig. i,the section slopes so much that the
anterior part is excluded, in. Intermediate nerve, n.st’. — n.st:’. The five pairs of large nerves. nx. — n6. The six pairs of
fine nerves. oc.m. The oesophageal commissures, t.cm. Large tiansverse commissures, c.m. Fine transverse commissures
which are, however, not usually, seen in their whole extent, cm’. The pair of laige ganglionic cells is, here, seen in
connection with the commissure.
3. M. graffi, n. sp. (Zeiss CC. Oc. 1. Borax-carmine. Picric acid.) Ideal horizontal section of the ventral nerve-cord,
constructed from a series of sections. The litera-significations are the same as in figs. 1 and 2. tc. A third description of fine
transverse commissures, found, solely, in this species, probably pertaining, originally, to the large transverse
commissures (tc.m.).
4—7. M. cirriferum, F. S. L (Zeiss CC. Oc. 2. Cam.-luc Osmic acid. Borax-carmine.) Four succesive horizontal sections
through the ventral nerve-cord. Of these, fig. 4 is the most ventral, and fig. 7 the most dorsal. The litera-significations
are the same as in the preceding figures. In fig 4, most of the intermediate nerve (i.n.) is seen; the section slopes so
much anteriorly, and ventrally, that in the opposite end some transverse commissures become visible, a. Ganglionic cells. In
fig. 5 a part of the intermediate nerve (i.n.) is still risible, tcm. Posterior large transverse commissure, seen to communicate
with lateral groups of ganglionic cells. Fig. G. a. The anterior segment from which the oesophageal commissures (ocm.)
and the first pair of fine nerves issue. In fig. 7, m. Many dorsally situated ganglionic cells are transsected. o.c.m.
Oesophageal commissures, transsected in their recurved course.
8. 31. giganteum, n. sp. (Zeis CC. Oc. 4. Cam.-luc. Borax-carmine. Picric acid.) Transverse section through the anterior
extremity of the ventral nerve-cord. n.st’. 1st pair of large nerves, on whose exterior side the 2nd pair of fine nerves occur.
b. and c. Points where the prolongations from groups of cells converge and pass into the nerves. n’. Root of the 1st
pair of fine nerves, d. Groups of cells situated between these nerves and the roots of the commissures, f. Groups of cells
whose prolongations converge, forming a chiasma (a) with the prolongations of the opposite group, ß. Cuticular septa
originating in the membrane of the outer neurilemma-sheath.
9. 31. giganteum, n. sp. Dwarf-male. (Zeiss CC. Oc. 4. Cam.-luc. Borax-carmine. Picric acid.) Transverse section of
the mesial ventral cord. On the one side, the section has passed through the root of a large nerve, whilst, on the
opposite side, it has passed between two nerves. One of the large transverse commissures is seen in the middle, only partially
affected by the section, a. The point, in the commissure, where the prolongations of the mesial groups of cells (nc.) of
both, ventral and dorsal, sides converge, and traverse each other. On the ventral side, the gioups of cells are seen situated,
one on each side of the intermediate nerve (in.). b.b. Points, at the extremites of the transverse commissure, where
prolongations from groups of cells converge, and pass into ’.he longitudinal commissures, c.c. Latero-dorsal groups of cells,
whose prolongations communicate with the transveise commissure, d. d. Large cells, whose prolongations enter the
longitudinal commissure on the ventral side. e. Group of cells situated under the root of the large nerve (one cell only is seen
in this section). /. Group af cells, which send their prolongations directly into the large nerve (vide also fig. 16 b.).
» 10. 31. graffi, n. sp. (From photo, taken with a Seibert hom. im. 1/s- Borax-carmine. Picric acid.) Transverse section of
the ventral nerve-cord and circumjacent,parts, n.sk. Membrane of the outer neurilemma-sheath; its structure is not
uniform ; neither in consistency nor staining. The inner neurilemma-sheath is well developed, and consists of several layers.
in. Intermediate nerve. ch. Point where the prolongations of two large cells traverse each other. nc. Latero-dorsal
ganglionic cells. cJi. Branch of the intermediate nerve. m’. Muscles, m. m’’. Ventral muscles, e. Ventral ectoderm. m. e.
Ectoderm of the stomach.
» 11. 31. giganteum, n. sp. Dwarf-male. (Zeiss F. Oc. 2. Cam.-luc. Borax-carmine. Picric acid.) Mesial portion of a
transverse section through the ventral nerve-cord, showing a pair of the large dorsal ganglionic cells whose prolongations form
a chiasma (ch.) and penetrate into the longitudinal commissures on each side (vide also fig. 2 cm’, fig. 14 and Pl. IX, fig. 5, 6’.).
in. Intermediate nerve, nc. Ganglionic cells. /,-. Connective-tissue nuclei. /,■’. Less-staining connective-tissue nuclei (r).
me. Epithelium of the stomach.
12. 31. giganteum, n. sp. (Zeiss F. Oc. 2. Cam.-luc. Borax-carmine. Picric acid.) Mesial part of transverse section through
the ventral nerve-cord, n.s.k. Homogeneous membrane of the outer neurilemma-sheath, from which septa (/.) proceed into
the ventral cord, and separate the groups of cells, whilst, a few septa pass to the membrane of the intermediate nerve (in.),
which gives off a branch that passes into the longitudinal commissure at b.; the fibrils of this branch are seen to issue, one,
from each of the few nervous tubes of the intermediate nerve, nc., nc. Two ganglionic cells whose prolongations traverse
each other; vacuoli are seen in their protoplasm, (probably artificially produced). nc-". Cell situated on the outer side
of nc., and which has its prolongations directed towards the converging point of the prolongations of nc., nc., nc’., nc"’.,
nc*. Ganglionic cells whose prolongation are, also, directed towards the same point. ne ’. Large cell corresponding to d
in fig. 9 and to Pl. IX, fig. be. a. Point at the extremity of a large transverse commissure which, in the section, is only
partly seen, and where ganglionic cells, that correspond to b fig. <), converge, c. The opposite extremity of the transverse
commissure entering into the longitudinal commissure. Some ganglionic cells are, also, seen here. d. 1 )orsal, coarse
longitudinal nervous tubes of the longitudinal commissure.
13. 31. giganteum. n. sp. (Zeiss, F. Oc. 2. Cam.-luc. Osmic acid, Hæmatoxylin.) Portion of a horizontal section through
the ventral part of the ventral nerve-cord, showing a problematic multipolar cell (a.) containing 2 nuclei; one of its
prolongations (b.) is seen to divide and, I think, become loosed out.
14. 31. giganteum, n. sp. (Zeis F. Oc. 2. Cam.-luc. Osmic acid, Hæmatoxylin.) Portion of horizontal section, showing the
»chiasma« formed by the prolongations of the dorsal pair of large ganglionic cells, (vide also fig. 2 cm’.).
» 15. 31. cirriferum, F. S. L. (Seibert hom. im. ’/16. Zeiss Oc. r. Cam.-luc. Osmic acid, Borax-carmine.) Portion of a
horizontal section through the ventral nerve-cord, showing the connection between the dorso-lateral ganglionic cells (nc.)
(corresponding to c. fig. 9), and the large transverse commissure situated between the 2nd and 3rd pair af large nerves.
nc. Large pair of ganglionic cells. /.’. Connective-tissue nuclei. One of the tine transverse commissures is, also, partly seen.
» 16. 31 giganteum, n. sp. (Zeiss, F. Oc. 1. Cam.-luc. Borax-carmine, Picric acid.) Portion of a transverse section, through
the ventral nerve-cord at the root of a large nerve, where a dorsal group (b.) of ganglionic cells is seen that send their
prolongations, direct, into the nerve, g. Septa of the nerve, c. Dorsal part of the fibrillar mass passing into the nerve, and
isolated by a septum, d. Group of a few ganglionic cells situated under the root of the nerve (vide also Pl. IX, fig. 6, a and
fig. 4 & 5, >’5.). f. Connective-tissue membrane, a. Gump of ganglionic cells (a. and b. correspond to c. and f. in fig. 9).
n.sk. Outer neurilemma-sheath.
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