NUCLEI OF MUSOLE-FIBRE IN NECTURUS LATERALIS. 461 



On the Nuclei of the Striated Muscle-Fibre in 

 Necturus (Menobranchus) lateralis. 



By 



A. B. Macallum, B.A., 



Fellow of University College, Toronto, Canada. 



With Plate XXXIII, figs. A and B. 



While examining, several montlis ago, some preparations 

 made for the purpose of demonstrating the mode of nerve 

 termination in the striated muscle-fibre of Necturus, I found 

 many of the isolated nuclei to possess on their surface furrows 

 and striations hitherto undescribed, and which, I now believe, 

 are of importance in determining the structure of the contractile 

 element of muscle-substance. A careful study of these nuclei 

 has further revealed other peculiarities which point to a conclu- 

 sion as to the origin of the contractile element, the muscle 

 reticulum. In view of this, I give a detailed description of the 

 appearances presented by the nuclei, and refer them to their 

 supposed causes. 



The best preparations were obtained with gold cbloride and 

 formic acid. This method is valuable for two reasons, the 

 nuclei are completely isolated after a stay of thirty to forty 

 hours in the acid, and the furrows on their surface take a deep 

 violet tint, while the remaining portion of the nuclear membrane 

 is coloured light, or rose violet. The isolation of the nuclei from 

 the muscle-substance prevents any confusion which might be 

 caused by the striation of the muscle-fibre were one to examine 

 them in situ. It is to be noted that the muscle-fibre in 



