562 DB. H. CHABLTON BASTIAN ON THE ANATOMY AND PHYSIOLOGY 



which certain processes are given off, project into the general cavity of the body*. 

 These several cells are in close apposition with one another, and are accurately dove- 

 tailed together, as can be well seen in transverse sections (Plate XXV. fig. 13) ; these also 

 show that the attached portion is the narrowest part, the free edges being thicker and 

 rounded. The section of each bundle, according to its size, exhibits more or less gra- 

 nular matter in its centre, which in the smaller and medium-sized bundles is completely 

 enclosed by the striped fibrous portion of the cell, whilst in the larger the central 

 cavity and contained granular matter become more distinct and communicate with 

 a more or less pronounced, bladder-shaped, fibrous prolongation (Plate XXIII. figs. 5 & 8). 

 Now if we imagine the sides of one of the flat cells described in Spiroptera oMusa to 

 grow up, approximate to one another, and close in completely over the granular matter 

 except at its central portion, we should have a formation similar to that just described 

 as actually existing in the Ascarides. A section of either extremity of the cell would 

 also show granular matter completely enclosed by the fibrous contractile portion, whilst 

 one through its centre would reveal a continuity between its central cavity and that of a 

 small fibrous prolongation from it. The two forms are thus seen to be only modifica- 

 tions of a common plan, between which a complete series of transition states can be 

 recognized in the structure of the muscle cell as met with in other different Species of 

 Nematoids (Plate XXVI. fig. 3). When one of these triangular cells of the Colomyarice 

 is seen lying on its side, it seems to be made up of a number of fine fibres, having a 

 longitudinal direction and a parallel closely packed arrangement, with no trace, however, 

 of transverse striation (Plate XXIII. figs. 8 & 9). But in transverse sections it is seen 

 that what appear to be simple fibres when viewed from the exterior, are in reality a 

 series of band-like fibres, each of which extends from the exterior to the central granular 

 matter of the cell (Plate XXV. fig. 13). No appearance can be detected leading one to 

 believe that these apparent bands are composed really of transverse rows of narrower 

 fibres. This structure of the contractile portion of the body of the muscle-cell is essen- 

 tially similar in both Colomyarice and Platymyarice. 



Much difference exists, both amongst the two groups and in the several members of 

 each, as to the degree of complexity of the remaining processes of the muscle-cell. 

 They are usually more simple in the Platymyarice. But in Nematoids generally we may, 

 I think, recognize two distinct varieties of these processes, the one being more or less 

 developed representatives of the bladder-like growths so distinct in Ascaris lumbricoides, 

 and the other answering to the transverse processes (Fortsatzen) extending from the 

 muscle-cells to the median lines — also well developed in the same animal (Plate XXIII. 

 fig. 2). The bladder-like processes are frequently but very little developed, and may 

 be seen in their simplest condition in Spiroptera ohtusa, where they are merely the 

 internal bounding portions of the muscle-cell, composed of fibrous walls (Plate XXVI. 

 fig. 21) enclosing the granular matter and contained nucleated cell, which rest on its 



* After maceration for two or three weeks in dilute nitric acid the muscles are readily resolved into their 

 component cells. 



