234 
CHAS. H. o’dONOGHUE. 
PLATE 23. 
[The drawings were all made at the same magnification by means of a 
camera lucida with a y^-in. oil-immersion objective and a No. 2 Zeiss 
ocular.] 
Fig. 11. — (x about 560.) Transverse section of the mammary out- 
growth in the pouch young twenty weeks after birth (i . e . Series 2) 
showing the two-layered condition of its wall. The fibrillar cells (/.) 
of the conjunctive tissue also show and it will be seen there is no 
membrana propria. 
Fig. 12. — ( x about 560.) Transverse section of part of one of the main 
ducts in the teat while the gland is at rest (i. e. Series 3). The wall is 
composed of a stratified epithelium four or five cells thick, and a 
coagulum (c.) is present in the lumen. 
Fig. 13. — ( X about 560.) Transverse section of two tubules of the rest- 
ing adult mammary gland (i. e. Series 3). The wall is characteristically 
two-layered ; a coagulum (c.) is present in the lumen. The fibrillar cells 
(/.) do not form a membrana propria. 
Fig. 14. — ( X about 560.) Transverse section of a tubule of gland 
during growth, when ovulation was not followed by pregnancy (i . e . 
Series 28). Solid bud-like outgrowths are present in, one of which a 
mitotic figure (m.) is shown. 
Fig. 15. — (x about 560.) Transverse section of two tubules at the 
stage of maximum growth activity (i.e. Series 9). Several stages of 
mitoses ( m ) can be recognised and the coagulum (c) is present. 
Fig. 16. — ( X about 560.) Transverse section of a fully formed alveolus 
some time after the attachment of the embryo to the uterus (i.e. Series 
16). The wall is single-layered and no membrana propria is present. 
Fig. 17. — (x about 560.) Transverse section of an alveolus at the 
commencement of milk secretion (i.e. Series 21). The cells are 
granular, and a fat-globule (o.) is present in one of them. The lumen 
contains milk (m.c.) 
Fig. 18. — (x about 560.) Transverse section of a corner between 
three alveoli when the gland is fully active and its lumen distended with 
milk (i.e. Series 25). This shows the enormous increase in the size of 
the alveoli. Enclosed between the single-layered alveolar walls ( w .) are 
several fibrillar cells (/.), which are now approximated to the alveoli. An 
enormous quantity of milk coagulum (m. c.) is present. The cells are 
granular and contain fat globules (o.). 
