370 WM. L. TOWER, 



ganglionic cells or any of the protecting or "binding" cells charac- 

 teristic of other portions of the nervous system. They do not give 

 off branches in any part of their entire length, but are simply con- 

 nectives between the anterior ganglia and the main portion of the 

 central nervous system - - the pair of large cephalic ganglia. 



The large cephalic ganglia are situated in the posterior part of 

 the scolex, a little behind the acetabula, one on each side of the 

 sagittal plane. Each of these cephalic ganglia consists of a large 

 rounded mass or body (compare PI. 21, Figs. 1 and 5, and PL 22, 

 Fig. 8) with a fairly smooth even surface and two projections or 

 horns. The anterior median side of each is prolonged anteriorally 

 into a conical process, the anterior horn (PI. 22, Fig. 8 conu. a), which 

 receives the fibres of the cephalic connectives of its own side. The 

 lateral portion of each ganglion is also prolonged into a cone-shaped 

 structure, the external horn (conu. ex), which contains the fibres of 

 the lateral nerve. The two ganglia are connected with each other 

 by a relatively small commissure (PL 22, Fig. 8 corns), the fissure 

 between the ganglia in the median plane being deep, especially in 

 front and behind. 



The body of the cephalic ganglion is made up of a core of 

 ganglionic cells traversed by nerve fibres and a cortical portion com- 

 posed almost entirely of fibres, the whole being enveloped in the 

 richly branched "binding" cells. The ganglionic cells are not as large 

 as those in the ganglia of the proglottides , but they are like them 

 in every other respect. Many of them are multipolar, and are often 

 richly supplied with branching processes (PL 24, Fig. 18). The nuclei 

 are relatively large, spherical, hyaline, with a deeply staining nucleolus 

 but no chromatic network ; the nuclear membrane is thin, has irregular, 

 thickened places, and in some instances a shrunken appearance, very 

 much like that found by HODGE (1892) in the spinal ganglia of Verte- 

 brates after a day's exercise, or after artificial stimulation. In the 

 cell shown in PL 24, Fig. 18 the dendritic or protoplasmic processes 

 are very numerous, but in VOM RATH preparations they are not easily 

 followed. Some of the nerve processes of such ganglionic cells have 

 deeply staining thickenings occurring at about equal intervals, as 

 may be seen in some of the processes of Fig. 18. Bipolar cells are 

 much more common than those of the unipolar type, and occasionally 

 there is found a peculiar form (PL 24, Fig. 19), which might readily 

 be taken for a unipolar cell, but which is in reality bipolar. The 

 cytoplasmic contents of these cells have the same stellate arrangement 



