368 THE SOLIDS. 



question but that such a mode of termination, though not 

 universal, is at least very frequent: thus, the arrangement of 

 the primitive nerve fibres in loops has been described by 

 Valentin, in the pulps of the teeth ; by Miiller, in the mem- 

 brana nictitans, and in the mucous membrane of the throat 

 of the frog ; in the papilla of the skin and tongue, by Todd 

 and Bowman. The loops are formed by one or more of 

 the nerve tubes, separating themselves from the bundle of 

 tubes composing every nerve of any magnitude, and after- 

 wards either passing into and mingling with those of a 

 neighbouring nerve, or else returning back to that from which 

 originally it started. 



It is now, however, very certain, that some at least of the 

 nerve tubes have a real termination : this is indisputably the 

 case with the single filaments which enter the Pacinian 

 bodies ; it has also been shown to occur with many of the 

 primitive tubes distributed to muscles. 



PACINIAN BODIES.* 



The Pacinian bodies are found in considerable numbers 

 attached to the cutaneous nerves of the hands and feet, espe- 

 cially to those of the extremities of the fingers and toes ; 

 they are also met with, though more sparingly, on other 

 spinal nerves, on the plexuses of the sympathetic, but never 

 on the nerves of motion, and in the mesentary ; in that of the 

 human subject, however, they are only with great difficulty 

 to be discovered owing to its thickness and the quantity of 

 fat usually contained in it : in the mesentary of the smaller 

 mammalia, as the cat, rabbit, &c. and more particularly 

 when these are in a lean state, they may be readily dis- 



* The discovery of these remarkable bodies constitutes one of the 

 happiest and most beautiful results of the application of the microscope 

 to minute anatomy. Pacini first noticed them in 1830, subsequently in 

 1835 ; but it was not until 1840 that he gave an account of them. (Nuovi 

 organi scoperti nel Corpo umano dal Dott Filippo Pacini, Pistoja). A. G. 

 Andral, Camus, and Lacroix, announced their existence at a Concours at 

 Paris in 1833, but do not appear to have recognized their real character. 



