TEGUMENTARY ORGANS 



427 



In fact, these nerve tubules are, as KoUiker pointed out, accompanied 

 by a delicate neurilemma and the axile corpuscle itself appears to me 

 to be nothing more than the enlarged end of this neurilemma. 



In Birds, a large proportion of the tegumentary nerves terminate 

 in bodies which are, on the one hand, related to these axile corpuscles, 

 and on the other to the well-known Pacinian bodies {fig. 322). 

 They are, in fact, usually described under the latter name ; but their 

 small size and superficial position, the paucity of their concentric 

 lamellffi, and the transverse striation of the solid central axis, ally them 

 closely with the corpuscula tactus. They are found in the skin 

 around the sacs of the feathers, 

 in the beak, and in the inter- 

 osseus spaces of the forearm and 

 leg. 



A special article (PACINIAN 

 Bodies) has already been de- 

 voted to the organs of this kind 

 which are met with in Mam- 

 malia, and it need only be added 

 here, that late researches have 

 shown that the Pacinian bodies 

 of mammals, like those of birds, 

 are solid masses of rudimentary 

 ■connective tissue ; the appear- 

 ance of capsules and of a central 

 ■cavity, arising merely from the 

 arrangement of the elastic ele- 

 ment and the extreme trans- 

 parency of the collagenous substance.^ They are, in fact, nothing 

 but thickened portions of the neurilemma, and the nerve which they 

 enclose either passes through them, or more usually terminates, 

 more or less abruptly, in the central solid axis. 



In the article on the PACINIAN BODIES reference is made to the 

 peculiar organs described by Savi in the Torpedines. These Savian 

 bodies, in fact, are little more than Pacinian bodies converted into 

 sacs by the development of a cavity between their central and 

 peripheral portions. Now Leydig has discovered that these Savian 

 todies do not stand alone, but that they form a part of a great series 

 of peculiar integumentary sensory organs, which are most characteristi- 



^ This fact was ascertained and stated independently and contemporaneously in 1853, by 

 Leydig and myself. See Quarterly Journal of Micr. Science, No. V., and Siebold and 

 KoUiker's Zeitschrift, B. v. Heft I. 



Fig. 320. — A papilla with its Corpusculum 

 tactus surrounded by three vascular papillae. 



