2O4 



HISTOLOGY 



cub.c. 



as the Meisner's corpuscles and the genital corpuscles, etc., differ from 

 this specimen merely in general shape, size, and the pattern into which 

 the terminal end fibrils are woven. 



In contrast to these two forms of touch organs in which a non-cellular 

 substance, a granular fluid, acts hydraulically upon the nerve-ending, 

 we must note three other kinds, all of which have capsules, but in which 

 the chief content, which is in direct contact with the nerve-ending, is a 

 solid cellular mass. These are the corpuscles of Herbst, the neuromus- 

 cular and the neurotendinous tactile organs. 



In the corpuscles of Herbst and some others that resemble it in struc- 

 ture, the nerve enters the melon-shaped, many-layered capsule (which is 



almost exactly like that of a Pacinian 

 corpuscle) and ends in a rod much as 

 in the cylindrical corpuscle. Instead 

 of being surrounded by a non-cellular, 

 fluid product of cells, however, it lies 

 in a single layer of heavy, cubical cells 

 which form a cylindrical covering 

 around it. These cells are thus placed 

 between the nerve-ending and the in- 

 nermost covering of the capsule. We 

 can find this organ, to study, in the 

 skin on the bill of the duck and other 

 waterfowl (Fig. 184). The inner cu- 

 bical cells are of unknown function, 

 but it is very probable that they act 

 as modifiers of the numerous jars, 



, trmrViPc ptr tn wVnVVi tVip Hurt 

 , . .., rubs > touches, etc., tO Which the dUCk 



rounding the reticular end-organs of the subjects its Sensitive bill in Order to 



A er DoGi^ r ) (From Anat ' ^ nz ' after learn the nature of ob J ects b y the 



delicate sense of touch. 



In the muscles and tendons of some vertebrates are found sensory 

 organs composed of spindle-shaped areas of the muscle or tendon tissue 

 itself, inclosed in a capsule and provided with the afferent fibers of sen- 

 sory touch cells that enter the capsule and branch freely on the inclosed 

 and slightly modified muscle fibers or tendon fibers within. These 

 organs record the pressures to which the muscles and tendons are sub- 

 jected during the contraction of the muscles, etc. If the pressure be- 

 comes too great, the sensation becomes one of pain. These are called 

 the neuromuscular and the neurotendinous organs of touch. In both of 

 them the method of distribution of the terminal organs is essentially 

 the same, but also very different from the pattern formed by these organs 

 in all the other touch structures. The fiber branches into several fibrils 



FIG. 184. Tactile (and taste?) nerve- 

 ending in the integument of a duck's bill. 

 Many concentric connective-tissue cap- 

 sules, fib.cap. cub.c., cubical cells sur- 



