ANATOMY OF THE CESTODA 



28 7 



Cu. 



A.m. 



- - Bs. 



L.m. 



Sc.c. 



recognized, besides the pores, which no doubt are concerned with 

 nutrition, spaces in which lie the ends of sensory cells. Close under 

 the cuticle lies the external layer of the parenchyma (basal membrane), 

 and below this the circular and longitudinal muscles forming the 

 denno-muscular coat. The matrix cells of the cuticle occur as in 

 the Trematodes, only on the 

 inner side of the peripheral 

 muscles in the external zone 

 of the parenchyma ; they are 

 fusiform cells, forming one 

 or two layers, but are not 

 arranged in the manner of 

 epithelial cells (fig. 184, Sc. c.). 

 They have fine branching 

 processes which run between 

 the dermal muscles, pass 

 through the basal membrane 

 and penetrate the internal sur- 

 face of the cuticle with small 

 pistil-like enlargements, ex- 

 panding on the internal 

 surface of the cuticle into 

 a thin plasma layer. 



In addition to the above 

 mentioned, there are other 

 cuticular formations occur- 

 ring on the cuticle of some 

 Cestodes, such as immobile 

 hairs and variously formed 

 hooks, such as are seen prin- 

 cipally on the scolex. Their 

 development is only roughly 

 known in a few species ; they 

 are usually already present in 

 the larval stage, and of the 

 same arrangement and shape 

 as in the fully developed 

 tapeworms ; a matter of 

 importance, because by these 

 structures larvae can be recog- 

 nized as being those of a certain species of tapeworm. 



The CUTICULAR GLANDS in Cestodes are scarce. 



The PARENCHYMA forms the chief tissue of the entire body, and in 

 all essentials its structure is similar to that of the Trematodes. 



P.m 



Sc.c 



L.m. 



O.s. 



L.t 



FIG. 184. Schematic representation of a small 

 part of a transverse section of Ligula sp. Bs., basal 

 membrane ; Cu., cuticle ; at its base are the end- 

 plates of the subcuticular (epithelial) cells; in the 

 centre a cuticular sense organ, O.s. ; F.v.s., vitelline 

 follicle ; Exc., excretory vessel ; C., calcareous cor- 

 puscle ; L.m., longitudinal muscles; M.c. myoblast ; 

 P.m., parenchymatous or dorso-ventral muscles ; 

 PL, plexus of nerve fibres ; A.m., circular muscles ; 

 Sc.c. t subcuticular or matrix cell; T.c., terminal 

 flame cell. 500/1. (After Blochmann.) 



