456 WINTERTON C. CURTIS, 



blunt processes of the oviduct wall (PI. 32, Fig, 11 ygT). Later they 

 become a much branched syncytium holding within it a few large 

 yolk cells and connected with the oviduct at many points (PI. 31, 

 Figs. 1 and 8, and PI. 32, Figs. 9 and 14 ygl). Where the branches 

 are continuous with the oviduct the structure of the two is seen to 

 be identical and the wall of the oviduct considered as such a delicate 

 syncytium is intelligible. Sections through the ovary show that it 

 consists of a ground substance in which the ova are embedded. At 

 the head of the oviduct the ground-substance is found to be directly 

 continuous with the oviduct wall and the same in structure (PI. 32, 

 Fig. 9). It seems therefore that the syncytium is continued out into 

 the ovary in the same way as into the yolk glands. Where the 

 ovary is found in a scattered condition (PI. 32, Figs. 9 and 11) this 

 is all the more striking and parts of the ovary are directly comparable 

 to the vitellaria in their relation to the oviduct (PI. 32, Fig. 9 ygl 

 and ov"). I am not able at present to give the carefull statement I 

 should wish regarding the history of the germinal and vitelline ele- 

 ments. If the nuclei of the syncytium in which the yolk glands are 

 found embedded become differentiated into yolk-nuclei (PI. 32, Fig. 14 

 yc) transitional stages should be apparent. Instead of this I find 

 the two kinds of nuclei almost always distinct and the yolk-cells 

 seemingly produced by the multiplication of those already there. In 

 any case one is impressed with the close resemblance in their actual 

 arrangement and appearance between portions of the ovary and the 

 yolk-glands. 



The uterus, seen in the dorsal and lateral views of the system 

 (PL 31, Figs. 1 and 8) is a slightly curved tube of uniform diameter 

 very much like the finger of a glove. It lies dorsal to the sexual 

 atrium in the parenchyma usually a little to one side of the mid-line 

 and ends blindly opposite the union of the two vasa deferentia. Its 

 walls are of large cuboidal cells resting on a delicate basement mem- 

 brane (PI. 31, Fig. 3 uc) beneath which are the fine circular and 

 longitudinal muscle fibres previously mentioned as continuous with 

 similar layers of the vagina. Regarding the function, it is of interest 

 to note that the terminal enlargement between the pharyngeal and 

 atrial chambers which in many forms presents a spacious cavity for 

 the reception of eggs and spermatozoa does not exist and that spermato- 

 zoa are not found in the uterus but do occur all along the lumen 

 of either oviduct (PI. 31, Fig. 6, and PI. 32, Figs. 9, 11 and 14 spz) and 

 collected at the head in a compact mass almost within the ovary 



