2 PROCEEDII-TGS OF THE NATIONAL MUSEUM. vol.61. 



central portion of the botbria is continuous with the parenchymatous 

 tissue of the strobile. The longitudinal muscle fibers of the strobile 

 continue into the bothria, where they radiate to the external dense 

 layer to which they are attached. It is the unequal contraction of 

 these muscle fibers which causes the crumpling and folding of the 

 bothria. A loop of the water-vascular system enters each bothrium 

 where it follow^s a course in the main parallel wath the margin, and 

 distant from the margin about one-fourth the diameter of the 

 bothrium. 



Ganglion cells were noted in sections of the scolex in the following 

 situations: In the axial parenchyma and myzorhynchus where they 

 were relatively few and small (fig, 11). Larger cells were noted in 

 the bundles of muscle fibers, "in the pedicels, and central portions of 

 the bothria. Others were noted in the dense superficial layer, appear- 

 ing to be relatively more numerous in the central portions of the 

 bothria ; others in the compact tissue of the auxiliary suckers, and in 

 the superficial layer of the back of the bothria. The ganglion cells of 

 the dense tissue, and many of those which are associated with muscle 

 fibers in the parenchyma, are characterized by having large nuclei 

 with conspicuous nucleoli, the cytoplasm much branching and with 

 rather indefinite limits (fig. 12). The cells belonging strictly to the 

 parenchyma, and some of those which are associated with long muscle 

 fibers have definite outlines, which are more or less oval. One of these 

 small oval-elliptical cells measured 0.012 mm, in the longer diameter ; 

 near by was another 0.03 mm. in diameter, with a nucleus measuring 

 0.012 and 0.009 mm. in the two principal diameters. Figures 12, a to /, 

 are camera lucida stretches of ganglion cells as they appeared in a 

 series of sections of a scolex. 



Strohile. — Eather slender, linear and flattened throughout. Seg- 

 ments begin a short distance back of the scolex as crowded trans- 

 verse lines. The proglottides are at first very much broader than 

 long, ultimately becoming squarish, then longer than broad. Ma- 

 turing and adult proglottides longer than broad, with bluntly 

 rounded angles. Free proglottides much longer than broad, the 

 anterior end usually more or less rounded or knob-like. 



In a specimen mounted in balsam, at a point 3 mm. back of the 

 scolex, where the strobile was 0.6 mm. in breadth, the proglottides 

 were 0.04 mm. in length. This specimen was 12 mm. in length. The 

 last four proglottides averaged 0.42 mm. in length ; the breadth was 

 0.28 mm. The last segment was more slender and longer than the 

 preceding three, which did not differ much in length and breadth. 

 The length of the posterior segment was 0.7 mm.; its breadth was 

 0.21 mm. at the anterior end, tapering to 0.12 mm. near the pos- 

 terior end. The last 10 segments of a larger strobile averaged 0.9 



