72 C. r. MARSHALL. 



are hence favorable for the study of the structure of mus- 

 cular fibre, which '' seems to lead to that view of the structure 

 of compound striated fibres advocated by Retzius, Bremer, 

 Melland, C. F. Marshall, and others ; the only point of 

 importance in which there seems reason for dissenting from 

 that view being with reference to the relation of the trans- 

 verse networks to the fibrils/' The chief differences between 

 the network Haswell describes and that described by the 

 above observers are these : (1) He states that the transverse 

 networks are not only in the interspaces between the 

 " fibrils/' but partly also penetrate them. (2) The longitu- 

 uinal networks, though mostly longitudinal, have oblique 

 strands and anastomoses. (3) The transverse networks some- 

 times appear as rows of spindle-shaped granular bodies, but in 

 crushed specimens he says these are seen to consist of a close 

 reticulum of delicate threads, the spindle bodies being con- 

 densed parts of it. (4) The distance between the transverse 

 networks is much greater. 



Haswell regards the '' fibrils " as the contractile part, and 

 not the network. 



I shall refer to Haswell's observations again in the subse- 

 quent portions of this paper. 



A. B. Macallum^ has published some interesting observa- 

 tions dealing with striped muscle. He confirms the existence 

 of the network of Retzius, Melland, and others, and considers 

 it the contractile part of the fibre. He states that the muscle- 

 nuclei are marked by furrows, sometimes transverse and some- 

 times longitudinal, and that these are probably caused by pres- 

 sure of the trabeculse of the network. He also states that in 

 some nuclei there is an intra-nuclear network similar to that 

 of the fibre itself. 



It thus appears that the view of the existence of a true 

 intra-cellular network in striped muscle-fibre has received 

 much support, and has been confirmed by several recent 

 observers ; and that the view held by Rollett and others that it 

 ' "On the Nuclei of the Striated Muscle-fibre in Meuobrauchus," 'Quart. 

 Journ. Micr. Sci.,' 1887. 



