DISPOSITION OF THE ORGANS. 749 



inclined to connect it with Ligula, especially because of the longi- 

 tudinal furrow in the median line of one surface of the body, which 

 he collates with the sulcus longitudinalis, regarded by the descriptive 

 helminthologists as characteristic of the genus Ligula. To this I shall 

 afterwards refer, only noting here that the sulcus longitudinalis of 

 Ligula is brought about only by the thick ventral line of genital 

 apertures, and cannot therefore occur in the worm under discussion, 

 nor indeed in any of Diesing's larval genus Sparganum. 



The parenchymatous, or, as we said in our diagnosis, fleshy con- 

 sistency of this worm is chiefly the result of the connective-tissue 

 matrix, which forms by far the greatest portion of the larval body. 

 No cellular texture is demonstrable. It is a homogeneous mass of 

 clear appearance, by no means compact, and resembling a gela- 

 tinous material rather than the ordinary connective tissue. The 

 uniform appearance is only interrupted by deposits small, tolerably 

 abundant, uniformly scattered calcareous corpuscles by muscle-fibres, 



FIG. 403. Transverse section through the larval body of 

 Boihriocephalus liguloides. 



and by vessels. Other organs, and especially generative organs, are 

 absent, except two nerve cords, which a careful examination of cross 

 sections reveals on the borders of the middle third of the body, as in 

 B. latus. The structure of the muscular apparatus is especially charac- 

 teristic in its deviation from that of the adult Bothriocephalw. There 

 is no division into cortical and median layers, for there is no develop- 

 ment of a distinct transverse or circular musculature, such as occurs 

 in all other Cestodes. This worm possesses, indeed, numerous strong 

 muscle-strands, but, with the exception of those beneath the cuticle, 

 they all run longitudinally, and never combine in large masses. Single 

 bundles, formed by the grouping of fine refringent fibres, run parallel 

 to one another, separated by larger or smaller intervals. These bundles 

 are thickest near the nerve cords, where the parenchyma is more com- 

 pact, forming distinct longitudinal strands, 1 which can be traced in 

 transverse sections along the whole length of the body. We have 

 here the explanation of the fact that the middle of the body-surface, 



1 It was apparently in reference to these longitudinal tracts that Diesing said of his 

 Ligula rcptans (loc. *.)" Tractus intestinalis bipartiti crura parallela in nonnullis saltern 

 individuis conspicua." 



