The nervous system in the Cestode Moniezia expansa. 377 



(PI. 21, Fig. 3), are nearly as good. The nerve fibres, on passing 

 into and out of the ganglion, pursue almost every possible direction, 

 making a tangle that I have not been able to unravel; yet there 

 appear to be certain paths within the ganglion that are recognizable, 

 owing to the number of nerve fibres which take the same direction. 

 The ganglionic cells associated with the nerve fibres appear in Fig. 28 

 (PI. 25) and Fig. 31 (PI. 26) to be of a rounded form, but they are in 

 reality multipolar, since they each possess numerous protoplasmic pro- 

 cesses. Isolated cells from this ganglion are shown in Figs. 16 and 

 17 (PI. 24) more highly magnified. Two kinds of these nerve cells 

 may perhaps be recognized, differing in size and in the richness of 

 their branching; those which lie in the center of the ganglion are 

 larger and more richly branched, while those at the periphery are 

 smaller, usually bipolar, and less richly branched. Otherwise the cells 

 are alike. The nucleus is rather small, compared with the nucleus of 

 a ganglionic cell of the scolex, and hyaline, and it contains a deeply 

 staining nucleolus. In some cases under a very high magnification a 

 faint chromatic reticulum may be seen in the nucleus. The nuclear 

 membrane is very thin, with no observed thickenings, and shows no 

 such wrinkles as are often seen in the scolex. The coarsely granular 

 cytoplasm is gathered into a mass about the nucleus, from which films 

 and threads of similar appearance radiate through the more finely 

 granular cytoplasm that occupies the periphery of the cell. Therefore 

 these cells invariably have a stellate appearance. 



There are also ganglionic cells that lie just outside the ganglion 

 and send their nerve fibres for the most part into the ganglion. These 

 cells are usually multipolar, possessing a few dendritic processes. 

 The nucleus is small, with a large, deeply-staining nucleolus (PI. 24, 

 Fig. 16), and very frequently a well developed chromatic reticulum. 

 The cytoplasmic contents present the usual stellate appearance. I 

 have not yet found in the posterior lateral ganglion of the mature 

 proglottides any of the richly branched binding cells found in the 

 younger proglottides. Either they are not present (which I can hardly 

 believe), or, more likely. Vom Rath's method will not differentiate 

 them sufficiently in the mature specimens. 



Upon the lateral nerve, at about the point where it crosses the 

 sexual ducts in their passage to the gonopore, there is another ganglionic 

 enlargement — the anterior lateral ganglion {gn.l.a, PI. 22, Fig. 6, 

 PL 23, Fig. 12). This is a dorsal enlargement of the lateral nerve 

 due to the accumulation of ganglionic cells at that point (PI. 26, 



25* 



