120 SPECIAL HISTOLOGY. 



in the main, of a sometimes more homogeneous, sometimes more 

 distinctly fibrillated collagenous substance, which there is no 

 reason to distinguish from connective tissue, and of fine elastic 

 fibres in different stages of development, as fusiform cells (cor- 

 puscles of the connective tissue, of Virchow), cell networks, 

 isolated fine elastic fibres and fibrous networks. These elements 

 are so distributed, that in most papilla a cortical layer and an 

 axile tract can be distinguished. In the former the fibrous 

 elements are disposed longitudinally, and the connective tissue 

 is often distinctly fibrillated, with the exception of the most 

 superficial layer, which forms a clear, homogeneous but not 

 separable margin. In the latter, on the other hand, the sub- 

 stance is more uniform and clear, and in many places is separated 

 from the outer layer by transverse elastic fibres. When these 

 latter, true elastic fibres are not very closely disposed, no one 

 would be led to consider that there is anything peculiar in this 

 arrangement ; but undeveloped and very close together, as they 

 are in Wagner's corpuscles, it is otherwise. These are, in fact, 

 nothing but the clear axis marked by transverse nuclei and 

 nucleated fibres, which I have already described ; and, if no 

 reagents be added, they present no other appearance than that 

 which I have figured in my ' Microscopic Anatomy/ fig. 4, or 

 in fig. 48 of this work. 



Dilute solution of soda, of which almost solely, I have 

 availed myself in investigating the course of the nerves in the 

 papillae, often does not render their contour at all more dis- 

 tinct, and I therefore paid no further attention to their struc- 

 ture ; while, on the other hand, acetic acid, which was also 

 employed by Wagner and Meissner, brings out the axes of the 

 papillae generally, though not always, as oval, or cylindrical, 

 more sharply-defined bodies, to which the numerous trans- 

 verse striae give a certain vague similarity to a fir-cone (fig. 

 54). In its more intimate structure, such an " axile cor- 

 puscle," as I call it, does not consist of superimposed discs, 

 as Wagner supposes, but of an internal mass of homogeneous 

 connective tissue, which is most distinct in transverse sections, 

 and when viewed from above; and of an external generally single 

 layer of undeveloped elastic tissue, which, in the form of fusi- 

 form cells, probably connected together and, more or less, 

 drawn out into fine fibres, with shorter or longer nuclei 



