752 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [34] 



a wrinkle when viewed from the exterior. This fact explained the dif- 

 ficulty experienced in finding the marginal apertures with a superficial 

 examination. The lateral apertures seem to be designed for the escape 

 of ova. 



The mature segments, as shown by these sections, are simply sacs 

 with muscular walls for the protection of the eggs. A transverse section 

 is long oval, 2.6 by l mm . The lateral muscular walls are from .1 to .16 mm 

 thick, the marginal walls from .16 to .24 mm thick. The segments are 

 separated from each other by a narrow partition from .02 to .06" 11U 

 thick. A few irregular shreds of muscular tissue and delicate strands 

 of connective tissue extend into the hollow, central part of the segmeut. 

 Otherwise, the segments are filled with granular bodies about .03 mm in 

 diameter. In sections stained with baBinatoxylou these are colored 

 violet ; and each is closely invested in a transparent, unstained mem- 

 brane which has an irregular or tattered outline. Some of these gran- 

 ular bodies which lay near the muscular wall of the segment were in- 

 closed in a net- work of muscular and connective tissue. In these the 

 investing membrane was not so prominent as in those masses which lie 

 farther from the walls of the segment. It would seem, therefore, that 

 the membranous investment of the granular masses is a result of the 

 degeneration or transformation of the muscular and connective tissue 

 of the interior of the segment. In the vicinity of the lateral apertures 

 several collapsed shells of ova were observed. These were unstained, 

 and were .027 and .016 mm , respectively, in the two diameters. 



One undoubted ovum was seen with granular, stained contents, and a 

 very thin, transparent shell, .02 and .016 mm in the two diameters. In 

 order, if possible, to prove the real nature of these granular masses I made 

 transverse and longitudinal sections of postero-median segments. In 

 these segments the ovary is voluminous and composed of distinct nu- 

 cleated cells, nearly circular in outline and from, .008 to .014 inm in diam- 

 eter. The nuclei were about .0025 mm in diameter. The ovary lies at the 

 middle of the posterior part of the segment with its greatest length 

 transverse to the axis. It equals a little less than one-fourth the 

 breadth of the segment and about one-fourth the length. These pro- 

 portions must be subject to considerable variation, inasmuch as the 

 ovary disappears completely in the posterior segments. At its thick- 

 est point, the ovary extends from the inner limit of one lateral muscu- 

 lar wall to the other. The ova are already abundant in these segments. 

 They are enveloped in a proper shell, which is thin and has an irregular 

 outline, owing to a wrinkling of the surface. This wrinkling or corru- 

 gation of the surface is apparently due to a contraction of the proto- 

 plasmic contents. They are approximately circular in outline, their 

 average diameter being about .025 mm . From a comparison of sections 

 made from postero-median segments with those from posterior segments 

 I am led to believe that the granular bodies contained in the latter are 

 ova with incomplete membranous shells. 



