SSKK^m*] BOOKS, WITH SHORT NOTICES. 185 
distinguishable, because it is less provided with nuclei, which are 
usually arranged one after the other in two long rows, placed one 
at one side and the other at the other side of the club, and because 
it is almost always observed to be undivided. 
9. The internal club-shaped body takes its origin from the 
extensive proliferation of the sheath enclosing the nervous fibre, 
which proceeds to the Pacinian corpuscle. 
10. From the Pacinian corpuscles of mammifera there usually 
arises one nervous fibre, and very rarely two. In those of birds, 
there are never more than one fibre. 
11. Generally the nervous fibre loses its double contour in the 
act of penetrating the internal club ; sometimes, however, it retains 
it for a short distance after penetration. The loss of the double 
contour in the nervous fibre occurs suddenly, not gradually. 
12. In the Pacinian corpuscles of the mammifera the nerve- 
fibre rarely terminates without dividing. In those of birds the 
division of the nerve-fibre has very seldom been seen. 
13. The termination of the pale nerve-fibre never occurs but 
in cells, the numbers of which vary according to the number of 
filaments into which the nerve-fibre divides itself. 
14. From the medullary sheath outwards, the same consti- 
tuents are found in the pale nerve-fibre as in that having a double 
contour, of which it is the immediate continuation. The limiting 
membrane of the pale fibre of the Pacinian corpuscle has this 
peculiarity — it is without nuclei. It is continuous, in the same 
manner, with the delicate membrane of the terminating-cells. 
15. The pale fibre sometimes appears in long thin filaments, 
which can be traced from the nucleus to the terminating-cell. 
This circumstance gives rise to the reasonable presumptiom that 
the axis cylinder of a nerve-fibre may consist of various repre- 
sentative filaments of the minute processes of many nerve-cells. 
16. In man the Pacinian corpuscles of the hand and foot are 
abundantly provided with blood-vessels, which not only penetrate 
the corpuscles from both sides, but from other superficial points. 
The number of blood-vessels is greater in the Pacinian corpuscles 
of the foot than in those of the hand. 
17. In the human Pacinian corpuscles of the two parts men- 
tioned, there is almost always a corresponding capillary, which, as 
it were, touches the upper extremity of the internal club-shaped 
body. 
18. The Pacinian corpuscles of the mesentery of the cat, and 
those in the foot of the horse and the bull, possess but a small 
number of blood-vessels, which, as a rule, enter the corpuscle by 
the same side where the nerve-fibre enters, and very rarely at the 
opposite side. 
19. In the Pacinian corpuscles of the bird, and particularly in 
those of the pigeon, which occur in that short tract of skin which 
borders the beak, the blood-vessels come from the vessels of the sur- 
rounding parts, and when they have reached the external surface 
of the corpuscle, lose themselves in it, with many convolutions, 
