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CHAS. H. o’dONOGHUE. 
glandular epithelium with its granular cells in a state of 
slight activity. A trace of a secretion somewhat resembling 
colostrum is always to be found as a coagulum in the lumen 
of the tubules and ducts (figs. 12 and 13) until it is removed 
by the more active secretion of colostrum or milk. It would 
appear, then, that the gland, quite apart from the proper milk- 
flow, is the seat of slow secretory activity, although this 
secretion is quite different in microscopic appearance from 
true milk. 
A well-defined lymph-gland is situated close to the outside 
of the mammary glands and between them and the under- 
lying muscles of the body-wall. Wheu full grown it is about 
the size of a small pea, and it appears to be correlated in 
some way with the activity of the mammary gland, for it 
enlarges at the same time (fig. 5). 
Changes Prior to Ovulation. 
Professor HilPs observations show that a slight change 
occurs in the external appearance of the marsupium before 
ovulation, in addition to the swelling of the cloacal margin 
characteristic of heat, the pouch being described as becoming 
tumid and also slightly moist internally. These external 
alterations are accompanied by corresponding changes in the 
microscopic appearance of the sebaceous and sweat-glands of 
the pouch area. 
The appearance of tumidity is caused iu large measure by 
the enlargement of the sebaceous glands, which commences 
just before ovulation and causes the lips of the pouch to 
swell. 
At the same time the sweat-glands become more active and 
more coiled. The increase in activity is marked by the 
epithelial cells becoming more granular and slightly larger, 
and at the same time the lumen of the gland is found to be 
partly filled by a secretion which, when it is discharged, no 
doubt causes the inside of the pouch to become moist. 
The mammary gland itself exhibits very little change 
