The Histogenesis of Cysticercus pisiformis. 199 



finally diiFerentiated muscle effected? Is it simply a condensation 

 of the originally loose parenchyma fibres into a compact bundle; or 

 is there a definite physiological differentiation of muscular material 

 from the undifferentiated parenchyma? I have no conclusive evidence 

 to offer on this point. The only evident difference between the 

 embryonic and adult muscle is one of staining reaction; the latter, 

 owing perhaps to greater density, shows a strong affinity for 

 haematoxjiin, and remains stained black when embrj-onic muscles in 

 other parts of the same section have lost the haematoxylin stain 

 almost entirely. But this difference may be accounted for solely on 

 the ground of a difference in density between embryonic and adult 

 muscles, for, if we examine a carefully stained section of a worm 

 partially contracted at the time of killing, it is seen that where the 

 muscles are contracted and consequently more dense, they have 

 stained entirely black; while, where they are expanded and con- 

 sequently less dense, they are stained very lightly. On the other 

 hand, it is difficult to conceive of a musculature as well developed 

 as it is in Taenia without an accompanying physiological differen- 

 tiation. 



According to the accounts of the many authors who have studied 

 the musculature in a large number of Cestodes, very considerable 

 variations exist. A detailed account of these, however, will not be 

 undertaken, only the principal differences which have been described 

 being noted. These are: a) the presence or absence of a nucleus, 

 b) the existence of a homogeneous, or a cross or longitudinally 

 striped, protoplasm, c) the possession of a sarcolemma, d) the differen- 

 tiation of an outer cortex and inner medulla, and e) the branched 

 or simple nature of the muscles. 



The difference of opinion as to the presence or absence of a 

 nucleus may be explained very readily by the fact that in some 

 cases the neuro-muscular cells are far removed from the muscles 

 themselves, and it is difficult without special methods to demonstrate 

 any connection between them, as, for instance, is the case with the 

 sub-cuticular muscles ; while in other cases the cells lie close to the 

 muscles and appear to form a part of their substance. The cross 

 striation of the muscles maj' be dismissed from our discussion, as it 

 has been described only for the Tetrarhynchidae by Pintner (1881) 

 and Sandeks (1870j. A longitudinal striation in the muscles of 

 Taenia is not readily demonstrable in most cases, but can be readil}^ 

 shown with high magnification in places where the muscle is 'flattened 



Zool. Jabrb. XXVI. Abt. f. Anat. 14 



