268 
PROGRESS OF MICROSCOPICAL SCIENCE. 
the water passed into the tissues and produced oedema. — In the dog 
the bundles of fibrillary tissue are mostly parallel to the surface 
of the cutis, and are held in their position by the elastic fibres which 
interlace amongst them. There are two kinds of cells in the stroma 
of the cutis. The nuclei of the one kind are spindle-shaped, of the 
other round. The cells with round nuclei are mostly found near the 
vessels, that is, in the superficial part of the cutis and in the sub- 
cutaneous tissue. It is suggested from their position that they are 
lymphatic cells. When digestion is far advanced, part of the Zell- 
platte which belongs to the cell with spindle nuclei, and which the 
author considers to be analogous to the Zell-platte of Schweigger- 
Seidel, is sometimes preserved. When digestion is not so far advanced, 
and the arrangement of the fibrillary bundles is undisturbed, it can be 
seen that the long axis of the spindle nucleus is parallel to the direc- 
tion of the bundles, and that the spindles lie between the bundles. It 
is inferred that the clefts between the bundles form spaces which are 
filled with lymph-fluid. As in the human skin, whilst the hair- 
follicles, fat-lobules, and sebaceous glands have each a separate blood 
supply from a small artery, the connective tissue between the fat, 
muscles, and glands is destitute of capillaries. The sweat-ducts (the 
popular idea that in dogs there are no sweat-glands is a mistake) open 
into the hair-follicle above the sebaceous gland, but at some distance 
from the epidermis. The sweat-gland is composed of a layer of flat 
cells, a structureless membrane on which these lie, and then the cells 
of the gland. A similar layer of flat cells has been described in man 
by Heynold, but he says that they are followed immediately by the 
gland-cells. The erector pili is composed of elastic fibres, which 
spring from a network which surrounds the hair-bulb, and which pass 
in a tract to the surface of the cutis, where they spread out and join 
the other fibres of the part. Between and amongst these elastic fibres, 
the smooth muscle-cells are insinuated. After prolonged digestion the 
bundles of fibrillary tissue undergo a change by which they present 
an appearance like that usually presented by muscular fibres. This is 
due to the gelatinous substance being dissolved, a sheath remaining, 
which, being thrown into transverse folds, simulates the transverse 
markings of muscle. Both the larger and the very fine bundles have 
such sheaths. When digestion is continued until the skin is reduced 
to a pulpy mass, what remains of the capillary blood-vessels is a very 
delicate structure composed of rows of spindle-shaped cells. 
