192 



THE ANIMAL PARASITES OF MAN 



their frequency and position in the parenchyma also varies, but 

 they are chiefly found in the cortical layer. They are the product of 

 certain parenchymatous cells, in the interior of which they lie like 

 a fat globule in an adipose cell. 



The MUSCULAR SYSTEM of the proglottides is composed of bundles 

 of fibres which lie immediately below the basal membrane, of 

 dorso-ventral fibres, and of muscle plates that are embedded more 

 deeply in the parenchyma. The sub-cuticular muscles (figs. 118 

 and 119) as a rule consist of a layer of circular muscles and of 

 longitudinal muscles, which are frequently also represented by only 

 one layer of fibres ; in other cases, however, the longitudinal fibres 

 extend to between and even beyond the matrix cells. The dorso- 



Ex.v. 



Cu. 



L.m. 



i^Si^^ 



L.m. 



Sc.c. 



- Sc.c 

 L.m. 



Tr.m. 

 T. 



r *',t*Vtr>- 





M.f. 





s **** ss:::: ^^ 



5m./. 



FIG. 119. Half of a transverse section through a proglottis of T&nia crassi- 

 collis. 44/1. Cu., cuticle ; Ex.v., exterior excretory vessel, to the right of 

 which there is the smaller internal one ; T., testicular vesicles ; L.m., longitudinal 

 muscles (outside and inside) ; M.f., lateral medullary fascicula with the two accom- 

 panying fascicula; Sc.c., sub-cuticular cells; 5m./., submedian fascicula; Tr.m., 

 transverse muscles ; Ut., the uterus, and represents the middle of the entire 

 transverse section. 



ventral fibres extend singly from one surface to the other, and at 

 both ends open out in a brush-like manner, and insert themselves 

 in the basal membrane. The deeper muscles consist of a peri- 

 pheral layer of longitudinal fibres, which are either disposed in 

 bundles or more evenly distributed, but in either case the number 

 of fibres or bundles considerably exceed the number of sub-cuticular 

 muscles. On each surface a bundle of transverse fibres follows 

 them, the elements of which penetrate to the borders of the segments, 

 thus passing through the longitudinal muscles and reaching the cuticle. 

 The mass of parenchyma included by the transverse muscles is 

 termed the MEDULLARY layer, while the mass lying outside them is 

 termed the CORTICAL LAYER. 



