80 C. F. MARSHALL. 



observers affords satisfactory evidence of the correctness of 

 their observations. 



The points of difference between the networks described by 

 Melland and Retzius are slight, the chief one being that 

 Melland figures the transverse networks in Dytiscus with 

 more polygonal meshes, and furnished with nodal thickenings 

 at the points of junction with the longitudinal bars of the 

 network. Retzius figures these in Locusta, but in Dytiscus 

 he describes the transverse networks as generally composed 

 almost entirely of radial fibres with very few transverse 

 connections; and in place of nodal dots he describes several 

 thickenings or nodes placed irregularly, and much fewer in 

 number than the nodal dots described by Melland. Melland 

 does not trace any connection between the network and the 

 muscle-corpuscles nor with the nerve endings. He shows how 

 the optical appearances of striped muscle are caused by the 

 network. He considers the network to be intimately con- 

 nected with the sarcolemma, and to be homologous with the 

 intracellular networks which have been described in other 

 cells. It is evident from fig. 6 of his paper that we have 

 to do with a true network and not a honeycomb, a fact 

 which is not so apparent from the figures of Retzius and 

 Bremer. I have reproduced the figure from Mr. Melland's 

 paper (fig. 18). 



Mr. Melland's results were obtained partly in conjunction 

 with myself, and the object of the present paper is a continua- 

 tion of this investigation. I have endeavoured to trace the 

 distribution of this intracellular network of the striped muscle- 

 fibre in the animal kingdom, and also, so far as possible, to 

 determine its function. 



The striation of muscle must not be confounded with a 

 transversely striated appearance caused by a corrugated outline 

 of the fibre, possibly due to a state of over-contraction. Such 

 a false striation is met with occasionally in some fibres in the 

 Echinus, Leech, &c, and is the cause of the muscles of these 

 animals having been described as striped. I shall, therefore, 

 only describe muscle as being striped when the striation is 



