THE BREAST MUSCLES OF THE FROG. 257 



were made upon the breast-muscle of the frog, while 

 my first inquiries were instituted upon the muscles of 

 the white mouse, I subjected this particular muscle of 

 the frog to the same process of investigation which I 

 had previously adopted in my researches in 1858-59, 

 which were published in 1860. The results of these 

 investigations will be understood by reference to the 

 drawings, which were printed in my paper published 

 in the Philosophical Transactions for 1862. 



Although the results of this further inquiry (1862) 

 were favourable to the view T had advanced, they 

 were deficient in this most important point, viz., 

 that the network which I had demonstrated over the 

 elementary muscular fibres of the mouse, PI. IX., 

 fig. 1, had not been conclusively demonstrated over 

 the frog's muscular fibres generally. Near the point 

 where the dark-bordered fibre divided to form pale 

 fibres, a network was easily demonstrated, PL IX, fig. 4, 

 but it could not in many instances be traced for any 

 great distance beyond this point. The following con- 

 clusions, however, were established in this memoir : 



1. That the nerve-fibres, as I had already stated 

 and as had been confirmed by Kolliker, were outside 

 the sarcolemma. PI. XI, figs. 1 and 2. > 



2. That the fibres might be followed for a greater 

 distance from the dark-bordered fibre than they had 

 been traced before, if the specimens were prepared 

 according to the new method of investigation which 

 I described. PI. XL 



3. The fine pale fibres were proved to be composed 

 of several finer fibres, which resulted from the divi- 

 sion of the dark-bordered fibre, as well as from the 

 division of the pale fibre in the sheath of the nerve. 

 PI. VII, fig. 2. The fine fibre accompanying the dark- 

 bordered fibres are demonstrated for the first time. 

 PI. IX, fig. 4. 



4. Contrary to the statements of continental ob- 

 servers, it was proved that the elementary muscular 



