586 A TEXTBOOK OF PHYSIOLOGY 



1. Several forms of end-organs or terminal corpuscles, such as 

 Meissner's corpuscles, Krause's end-bulbs, Ruffini's organs, and the 

 corpuscles of Pacini or Vater. Such terminal corpuscles consist of a 

 coarse nerve-fibre or knot of branches surrounded by a semifluid 

 intercellular substance enclosed in a capsule. 



Meissner's Corpuscles are oval bodies about 7r ^. to T -\- inch in 

 length. Each corpuscle consists of flattened cells surrounded by a 

 capsule, around which one or two medullated nerve-fibres wind, to 

 enter at the upper pole. The medullated coat is lost at the point 

 of entrance. These corpuscles occur particularly in the papillae of 

 the true skin, especially in the palms of the hands and in the soles of 

 the feet. 



Krause's End-bulbs have the form of an encapsulated bulb, the 

 ax on of the medullated nerve entering its lower extr amity to ramify 

 among the ovoid cells contained within the capsule. 

 They occur particularly in the conjunctiva, the mucous 

 membrane of the mouth, the glans penis and clitoris, 

 and the ligaments of joints. They also occur on the 

 under-surface of the toes of guinea-pigs and in the 

 wing of the bat. 



Euffini's Organs are found in the subcutaneous 

 tissue near the sweat glands, and in the corium of 

 the fingers and toes; they lack distinct capsules. 



The Pdcinian Corpuscle (Fig. 328) occurs in the 

 subcutaneous tissues of the palm, fingers, sole; in the 

 sexual organs ; in the deep layers of connective tissue 

 near joints; and in the mesentery. Each corpuscle is 

 of oval shape, and consists of forty to fifty lamellae 

 FIG. 326. END concentrically arranged. The lamellae are formed 

 BULB OF THE o f connective tissue, and covered with endothelium. 

 JTJNCTIVA. A lymph space exists between each lamella and its 

 (Krause.) neighbour. A medullated nerve-fibre enters at one 

 pole. Its axon passes through all the lamellae to the 

 central core of the corpuscle, ramifies therein, and ends in small 

 terminal buds near the distal pole of the corpuscle. 



2. Nerve-endings in connection with tactile hairs. Fine medullated 

 nerve-fibres form a network in the outer coat of the hair follicle, and, 

 losing their medullary sheath, run parallel to the hair, and finally 

 penetrate and end in the inner layer of the hair sheath (Fig. 329). 



3. Single nerve-fibres pass to the under-surface of the epidermis, 

 lose their medullary sheath, and divide into fine filaments, which end 

 among the cells of the epidermis (Fig. 330) . 



Various other special forms of nerve-endings have been described 

 in different animals for example, in the bill of the duck, the skin of 

 the whale, etc. 



Methods of Investigation. The sensation of touch or pressure 

 is investigated by a series of hairs of different thicknesses attached 

 at right angles to wooden rods. The hair is applied perpendicularly 

 to the skin, and the amount of pressure required to bend visibly any 



