FEELING AND TOUCH. 395 



the Pacinian corpuscles ; 2, that the tactile corpuscles and 

 those of Krause are only secondary forms of the same type; 

 and, finally, that this type, in opposition to that of the Pacin- 

 ian corpuscles, presents the closest analogy to the funda- 

 mental structure of the termination of the motor nerves. 



The form of the corpuscles of Krause, as observed in the 

 conjunctiva, appears to be that of the most elementary of the 

 nerve terminations : it consists of a nerve tube, with a double 

 outline, rolled up at its terminal portion, and deprived of its 

 medullary layer, swelling out as it loses itself in a mass of 

 nerve substance, exactly similar to that of the axis-cylinder, 

 containing central nerve cells; this tube is furnished with 

 nuclei, arid has as a covering only the prolongation of the 

 sheath of Schwann. The same type is found in Meissner's 

 or the tactile corpuscles : round the central portion the nerve 

 fibres are rolled up, with no interstices between them, and 

 transversely strewn with elongated nuclei, and thus the cor- 

 puscle gets that peculiar appearance which has been likened 

 to that of a pineapple, but which, according to Rouget, re- 

 sembles much more an ovoid and cylindrical ball of twine : 

 " errors in observation have led to the belief that the nerve 

 tubes terminate either in loose ends, or loops, on the surface 

 of the corpuscles. Beginning at the base of the papilla, the 

 nerve tubes emanating from the sub-cutaneous network turn 

 towards the axis and join the tactile corpuscle, either at its 

 lower extremity or at its middle portion ; sometimes passing 

 along the borders or the surface, they extend nearly to its 

 lower portion : if the place at which the tube with the double 

 outline appears to cease be carefully observed, we find that, 

 losing here its medullary layer, and the peculiar refraction 

 belonging to it, the gray, pale nerve fibre glides into the 

 interstice between the transverse stria3 of the corpuscle, and 

 disappears more or less suddenly from sight, penetrating 

 the interior of the cortical layers. In the central mass of the 

 corpuscle, the gray fibres with nuclei are not found, nor the 

 tubes with a medullary layer: this central mass is composed 

 of a finely granulated and extremely refracting substance, 

 furnished with nuclei, and exactly similar to that which forms 

 the nerve oif-shoots of the conjunctiva. ... It is extremely 

 probable that, as in the case of the ganglionic corpuscles, 

 the terminal plates, the terminal end of the electric plates, 

 etc., this is only a swelling or opening out of the peculiar 

 nerve element, the axis-cylinder" 



The short, gray, horizontal, and ribbon-like fibres, twisted 



