292 THE ANATOMY OF CESTODES. 



under the longitudinal bands. With a low power it often appears 

 as though we could, in a cross section, follow these fibres in a 

 ring round the middle layer (Fig. 144), but in reality we have here 

 to do with two flat muscular plates, whose fibrous bands enclose the 

 middle layer, and expand at the sides of the joints (Fig. 148) into 



Fig. 148. — Cross section of a somewhat older joint of Tamia 

 saginata. ( x 38. ) 



a fan shape towards the cuticle. Inasmuch as the bundles on either 

 side often converge, and even occasionally cross, it appears as if they 

 were in continuous connection ; and this is especially so, since many 

 of the sagittal muscles also usually bend round, and surround the 

 middle layer. It is not, however, only at the lateral borders of the joint 

 that the transverse fibres bend from their normal direction towards 

 the cuticle; the same appearance is to be observed (Fig. 148) here 

 and there throughout the rest of their course. This occurs sometimes 

 at so many points, especially in the young joints, that the longitudinal 

 muscles, separated by the processes, assume an almost radiate arrange- 

 ment, and present an appearance which reminds one of the fibrous 

 groups in the cortical layer of the spinal cord. 



Finally, as to the sagittal muscular fibres, these are mostly isolated 

 or united in slender bundles, which are stretched between the two 

 surfaces of the tape-worm, and were hence originally described by me 

 as dorso-ventral muscles. They are the thinnest of all the parenchymal 

 fibres, and run as fine fibrils almost straight across the whole thick- 

 ness of the body through both layers. In the outer layer they form 

 almost the only contractile elements, other miuscle fibres being but 

 rarely present to any considerable extent. It is, however, only in 

 their earlier stages that the sagittal fibres run at all straight, for the 

 development of the generative organs which finally grow throughout 

 the whole of the middle layer naturally influences their arrangement, 

 and often alters their direction. 



Lr direction, 

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