OBSERVATIONS ON STRIPED AND UNSTRIPED MUSCLE. 79 



as, according to him, it does not undergo important changes 

 in form during contraction and extension. He thinks that 

 the network is probably concerned in conveying the stimulus 

 from the nerve to the muscle-fibre. In support of this 

 he mentions that the fibre, as a rule, contracts simul- 

 taneously throughout its whole thickness; also that the 

 nerve-fibres are apparently connected with the transverse 

 networks. 



Retzius also examined muscle from Musca, Oestrus, Noto- 

 necta, Locusta, Astacus, Rana, and Triton. In Locusta the 

 transverse networks had more polygonal meshes than in 

 Dytiscus. In Astacus, Rana, and Triton the longitudinal bars 

 of the network were thicker than the transverse. 



In some cases he states that the longitudinal bars of the 

 network were not straight but zigzag. From the descriptions 

 and figures it is very probable that this appearance was due to 

 pressure, and is not normal. 



Bremer 1 also describes a well-defined network in the striped 

 muscle-fibre, evidently identical with that described by 

 Retzius. He states that the longitudinal lines are true fibrils, 

 and not part of cylindrical sheaths as Gerlach maintained. 

 He further traces the axis cylinder of the nerve into direct 

 continuity with the muscle-corpuscles. 



He considers the longitudinal striae of Gerlach to be 

 identical with the longitudinal bars of the network, and 

 explains the irregular dotted appearance, or " Sprenkelung," 

 of Gerlach's longitudinal striae as being due to imperfect 

 staining. 



Bremer's results, though published subsequently to those of 

 Retzius, were obtained quite independently. 



B. Melland 2 has recently investigated the structure of the 

 striped muscle-fibre, and has arrived independently at results 

 agreeing very closely with those of Retzius and Bremer. This 

 close correspondence between the accounts of these three 



1 « Arch, fur Mikr. Anat.,' Bd. xxii, 1883, pp. 318—356. 



2 "A Simplified View of the Structure of the Striped Muscle-fibre," 

 ' Quart. Journ. Micr. Sci.,' July, 1885. 



