86 EDWARD B. POULTON. 



necessary precursor of it), at first formed as large granules, 

 becomes gradually more fiuely granular, undergoing suddenly 

 a change which enables it to become coloured deeply by staining 

 fluids, and shortly after becoming entirely homogeneous. If 

 this be correct the granular cells must be looked upon as repre- 

 senting on a very large scale the stratum granulosum and 

 lucidum of skin, which are generally considered to be stages 

 in the development of the corneous condition reached at a 

 higher level. 



The difficulty remains, that outside the papilla no trace 

 of the granular cells is seen, although very similar cells are 

 met with at the surface, both within and without the papillae. 

 It also appears remarkable that the granular cells should be 

 applied at all stages of structure to the hair-like papillae, and 

 that the latter should receive accessions from the outside where 

 there are no granular cells, and from its own secondary 

 papilla, where the granular cells are not much developed. 



I have described the structure of these papillae minutely, 

 as they seem to me to be an entirely new and hitherto unde- 

 scribed type, modified in a remarkable manner for the capture 

 of small insects. 



Filiform papillae. — These are very large and long (1-5 

 mm. in length), and entirely normal in appearance. Their 

 direction is backwards in the row along the sides (limiting 

 the papillate surface), upwards and backwards among the 

 circumvallate papillse. They have no corneous investment, 

 and a large non-medullated nerve may often be seen in the 

 axis. It is therefore probable that they are tactile rather 

 than mechanical in function, a conclusion which is also con- 

 firmed by the greater specialisation of the peculiar papilla? 

 for these very mechanical purposes. The distribution of the fili- 

 form papillae is also strangely antagonistic to the view that they 

 are mechanical, and certainly not opposed to the supposition 

 that they are tactile. 



