138 Mr. W. J. Sollas on the 



marked effects. Thus on adding a 5 or 10 per cent, solution 

 of potash to a fragment of the teased-out tissue, the fibres at 

 once became swollen, those which were previously curved 

 straightened themselves out, and simultaneously the axial 

 thread almost completely disappeared ; on then adding a 

 10 per cent, solution of nitric acid the fibres at once con- 

 tracted, and the axial thread became more visible than it had 

 been before ; again adding potash the fibre expanded ; again 

 nitric acid, and it contracted ; and as often as one or the other 

 reagent was applied, so often the same results were produced. 

 With strong acid the outlines of the fibres appeared to vanish, 

 and a homogeneous substance remained behind, in which the 

 axial thread remained wonderfully clear and distinct; on adding 

 magenta, the threads stained deeply, but the matrix was 

 not affected. The fibres can best be separated from their 

 tissue by macerating thin slices for a few days in baryta- 

 water or 1 per cent, chromic-acid solution, and then teasing 

 out. 



The muscular layer passes at its distal margin insensibly 

 into gelatinous connective tissue with fusiform corpuscles. 

 The change seems to be accomplished by the loss of a distinct 

 border to the muscle-fibres, and the growth of the fusiform 

 axial thread at the expense of their hyaline portion ; at the 

 same time a distinct but small nucleus and nucleolus become 

 clearly visible in the axial thread, which has also acquired a 

 granular character (PI. VII. fig. 17). 



The muscles of the sphincter, are darker than those of the 

 rest of the muscular layer, owing to the increased size and 

 proximity of their axial threads and to the development of 

 fine granules in their hyaline exterior. 



With carmine or magenta the axial threads of the muscle- 

 fibres are easily stained, but the hyaline part not at all ; hence 

 when a section of the muscular layer is stained, the sphincters 

 are made very prominent, since their abundant nuclei lead 

 them to acquire a very dark colour. 



We have applied the term muscle-fibres to the structures 

 just described, because they are morphologically similar to the 

 fibres occurring in other animals to which no one hesitates to 

 apply the term " muscular ; " and the fact that, slightly modi- 

 fied, they enter into the composition of the sphincters of the 

 cortical funnels seems to show that they are functionally 

 muscles as well. If, then, functionally and morphologically 

 they resemble the organic muscles of other animals (and 

 Kolliker, Oscar Schmidt, Hackel, and F. E. Schulze all 

 seem agreed upon this point), one sees no good reason for 

 withholding from them the name muscular. The specializa- 



