NEW ASEXUAL TAPEWORM. 



827 



moreover, in the present worm the usual meshwork arrangement 

 of fibrils round spherical masses of the homogeneous ground- 

 substance such as occurs in so many tapeworms, and is often a 

 very coarse and thus more obvious network. The homogeneous 

 ground-substance was, however, traversed by two sets of fibres, 

 which are, I presume, muscular fibres. These are absolutely at 

 right angles to each other and not at all closely set in either case. 

 The dorso-ventrally running fibres are nearly always wavy in 

 their coui-se, the transverse fibres ai-e quite straight — a matter of 

 different states of contraction, as I imagine. 



The cortical layer is easily divisible into two regions, which are 

 of about equal diameter. The innermost of these is that occupied 

 by the bundles of longitudinal muscular fibres. The bundles of 

 muscular fibres are two or sometimes three deep, and each bundle 

 contains a large number of fibres, which, however, are not very 

 closely pressed together. In addition to these bundles of rather 

 slender fibres there lie on either side, between the nei"ve-cord and 

 the lateral margin of the proglottid, two bundles of considerably 

 stouter fibres which run continuously from segment to segment 

 and are closely associated with a longitudinally running cavity. 

 These bundles appear on occasions to lie actually within the cavity. 

 This tubular cavity is not at all like the tubes of the water 

 vascular system, and it lies within a very lax tissue. I am unable 

 at present to suggest its nature. 



The accompanying text-figure (text-fig. 115, p. 828) illustrates a 

 section through the hinder part of the worm not very far in front 

 of the budding region. This region shows very plainly a system 

 of irregular spaces in various parts of the body belonging to the 

 water vascular complex. It may be remarked first of all that the 

 dorso-ventral diameter is greater here than in the more anterior 

 part of the body. The structure of the vertical and medullary 

 regions is the same, but the lower central region of the medulla 

 actually forms a cavity (text-fig. 114 A) which I do not think to 

 be artifact and which may be a forward extension of the cavity 

 of the terminal bladder, though I have not proved the fact, from 

 an unwillingness to sacrifice the specimen altogether. The in- 

 terior lining of the space was, however, so very strongly stained 

 as compared with the surrounding tissues that it appears to me to 

 be practically certain that the staining fluid gained access through 

 the two cut ends of the piece of worm, which was stained en bloc. 

 This, of course, argues a continuous central cavity. 



It was quite plain that this cavity was quite distinct from that 

 of the transverse water vascular trunk. The peculiar cential 

 cavities occupying nearly the middle of a segment here and there, 

 referred to later (see p. 830) in describing sections made from 

 earlier segments in the body, are present hei"e and are again not 

 to be confused with the central lacuna. Their thick walls show 

 no trace of an opening into it. In addition to the main trunks 

 of the water vascular system, which are disposed here as they are 

 elsewhere in the body, there are scattered irregular spaces which 



