1914] A New Cestode from Amia Calva L. 109 



membrane — the yolk-cells within the follicular wall. That the yolk- 

 cells are semi-fluid in consistency cannot be doubted when one observes 

 them in their passage through the vitelline ducts, as noted above in 

 connection with the description of the latter, and as shown in Fig. 29b, 

 where the nucleus with its surrounding clear area is distending the wall 

 of the duct. The nucleus and, for that matter, the whole cell in many 

 cases, resembles that of the ova; in fact, it is often quite difficult to decide 

 which is the ovum in the egg-complexes to be found in the uterine tube. 

 In most follicles the smaller cells are arranged around the wall more or 

 less like an epithelium, as described by Sommer and Landois for D. 

 latus, while the larger ones are to be found in the middle. The wall itself 

 is a very thin membrane in which no definite nuclei were seen, although 

 small flattened nuclei situated between the yolk-cells and close to the wall 

 may belong to it. Perhaps the most noteworthy peculiarity of the yolk- 

 cell is the large almost clear area to be seen in the cytoplasm, often 

 surrounding the nucleus (Fig. 29), which is doubtless the fluid yolk which 

 will later be absorbed by the developing egg. 



A short distance from the point where the oviduct receives the com- 

 mon vitelline duct are located the shell-glands. Here the oviduct 

 expands slightly — to a diameter of 20fi. In most of the series examined 

 the shell-glands formed a sort of vacuolated mesh work, in which, although 

 there were to be seen well-developed nuclei, 4 to 5ju in diameter, it was 

 extremely difficult to distinguish individual glands. However, in one 

 series, where quite a length of oviduct was cut longitudinally, two or 

 three club-shaped unicellular glands could be made out (Fig. 30). Their 

 connections with the former were in the form of darkly-staining bars 

 traversing the epithelium between lighter areas of about the same widths. 

 Furthermore, numerous thread-like processes situated in the lumen, of 

 the oviduct and directed towards the uterine tube corresponded with 

 these dark bands, at least in position, since they were divided into groups, 

 each group being opposite a dark band, as shown in the figure. While 

 the outlines of the glands are quite difficult to discern, their connections 

 with the oviduct are readily seen in sections through the region in almost 

 any plane, tangential sections, for instance, showing dark circular spots 

 on a much lighter background. Again, in younger proglottides treated 

 with Mallory's stain, the glands and the otherwise dark bands appeared 

 much lighter than the epithelium, which fact further supports the view 

 that they are related anatomically. Thus, from the foregoing descrip- 

 tion, it appears that the processes in the lumen probably constitute the 

 material secreted by the glands, and that this material is passed along 

 from the bodies of the cells through the narrow necks which act as duct- 

 lets, suggestions which are strengthened by the facts that the so-called 



