76 C. F. MARSHALL. 



Dytiscus and other forms. This network consisted of (r.) transverse 

 networks placed at regular intervals, and corresponding in position 

 to Krause's membranes ; (n.) longitudinal bars parallel to each 

 other, and apparently running the whole length of the muscle-fibre, 

 and connected with the transverse networks. His results were 

 obtained partly by transverse and longitudinal sections, and partly 

 by teased preparations. He also employed the following method of 

 gold staining : the specimens were placed for twenty-five minutes in 

 i to \ per cent, gold chloride, either with or without previous 

 immersion in 1 per cent, formic acid; then in 1 per cent, formic 

 acid for ten to twenty hours, and exposed to the light. He gives 

 the following description of the muscle-fibre of Dytiscus : In the axis 

 of the fibre there are one or more rows of muscle-corpuscles, the 

 protoplasm of which is produced into several (2 — 5) processes, from 

 which finer processes arise forming the transverse networks. Each 

 muscle-corpuscle is in connection with five or six successive trans- 

 verse networks. The longitudinal bars of the network he describes 

 rather doubtfully as consisting of rows of dots (p. 8), but he de- 

 scribes and figures them projecting freely in some preparations. 

 The matrix is structureless, and is only slightly stained by the gold. 

 The sarcolemma is apparently closely attached to, but probably inde- 

 pendent of, the network. The nerve-endings appear to be in close 

 connection with the transverse networks. The function of the 

 network he was unable to determine, but states that it is probably 

 not merely a supporting framework, but actively concerned in con- 

 traction. He does not, however, regard it as the true contractile 

 part, 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 simultaneously throughout its whole thickness ; also 

 that the nerve-fibres are apparently connected with the transverse 

 networks. 



Retzius also examined muscle from Musca, Oestrus, Notonecta, 

 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. 



