464 A. B. MAOALLUM. 



author) in longitudinal and transverse trabeculse, the myosine 

 arising from that part of the cellular contents enclosed in the 

 meshes of the primitive reticulum of the cell. 



It is not too great an inference to draw that this reticulum 

 is the true contractile element, while the myosine shifts and 

 accommodates itself to the conditions of the latter. In support 

 of this I refer to fig. a, 6 and 13, in which one sees that the 

 furrowing takes the shape and arrangement of the meshes of 

 the reticulum. 



Why the furrowing on the surface of some nuclei is longitu- 

 dinal only, on others transverse, I cannot with certainty say. 

 Of one thing I am sure : where one series of parallel furrows 

 alone is visible, these are in by far the greater number of cases 

 transverse to the long axis of the nucleus. The greater part of 

 the muscle-fibre used in my preparations was in the uncon- 

 tracted condition, and it is in this condition that the muscles 

 are for the greater part of life. Following out the theory as to 

 muscular contraction, given in the last paragraph, it is to be 

 supposed that during rest the transverse trabeculae of the muscle 

 reticulum are contracted, but lengthened during contraction of 

 the fibre, the conditions with regard to the longitudinal trabe- 

 culae being in the reversed order. As now the contraction or 

 shortening of the transverse trabeculse must occur during the 

 greater part of the life of the muscle, or during its resting 

 periods, it is obvious that transverse furrows should be seen on 

 the nucleus oftener and more prominent than longitudinal ones 

 or than both combined. In this way we may explain away part 

 of the difficulty of accounting for the occurrence of one or other 

 series only of furrows. 



E. Weber^ found that the nuclei of the frog's muscle are 

 provided with longitudinal striae, which he thought due to the 

 pressure exercised by the muscular fibrillse. I endeavoured for 

 the sake of comparing them with the nuclei in Necturus to 

 isolate, after the manner already described, the nuclei of the 

 frog^s muscle, but I met with a very indifferent success. In 



^ " Note sur les noyaux des muscles stries chez la grenouille adulte," 

 ' ArcLives de Physiologic,' 1874, p. 489. 



