OBSERVATIONS ON STRIPED AND UNSTRIPED MUSCLE. 75 



larger pieces ; in such pieces the transparent substance bounding 

 Cohnheim's areas was stained red, and was thickened at the nodal 

 points. The muscle-corpuscles always lay in the stained substance 

 and not in Cohnheim's areas ; they consisted of a central oval 

 nucleus and a stained peripheral substance continuous with the 

 stained network of longitudinal striae. He states that the longi- 

 tudinal striae are very variable in thickness and always zigzag : 

 never straight. He regards them as thickenings of fine sheaths of 

 nervous matter enclosing the fibrillae of the muscle ; these sheaths 

 corresponding to the boundaries of Cohnheim's areas. 



He therefore concludes that the intravaginal nerve plexus and the 

 longitudinal striae are continuous, and together make up the isotropous 

 part of the muscle-fibre, and are to be considered as nervous. To 

 them belong also the muscle-corpuscles and the nuclei of the intra- 

 vaginal nerves. He regards the anisotropous matrix as the contractile 

 part. Gerlach thus appears to view the isotropous part of the 

 muscle, stained by the gold, as a honeycomb, and not a true network 

 of fibrils. He has apparently failed to observe the transverse net- 

 works, and does not attempt to explain the relation between the 

 network and the transverse striation. 



The existence of an intravaginal nerve plexus in the muscle-fibre, 

 and also the continuity of the nerve end plate with the isotropous 

 part of the muscle, have been denied by Ewald* and Fischer, f 



EngelmannJ regarded the isotropous part of the fibre as a struc- 

 ture " das in physiologischer Hinsicht von einem Nerven nicht 

 wesentlich abweichen wiirde," and suspected a connection with the 

 axis cylinder. 



In a later paper Engelmann § states that the contractility of the 

 muscle-fibre is always connected with fibrillar elements in the fibre ; 

 and he compares these with fibrillar elements in the protoplasm of 

 some of the Rhizopoda, Infusoria, etc. 



Ketzius || describes very carefully a network in the muscle-fibre of 



* "Arch, fur Mikr. Anat.," I5d. xiii., pp. 365—390. 

 t " Pfliiger'fl Archiv," Bd. xii., pp. 529—548. 

 I " ['Auger's Archiv," Jid. xi., p. 462. 

 § " PAnger^ Archiv," Bd. xxv., 1881, pp. 538—565. 



|| " Zur Kcnntniss del qucrgcstrciftcn Muakclfascr," "Biologische Unter.such- 

 ungcn," 1881, pp. 1—26, I'ls. i., ii. 



