12 - THE STRUCTURE OF MAN 
CUTANEOUS GLANDS (MAMMARY GLANDS) 
The cutaneous glands of Man fall into two classes: sweat- 
glands and sebaceous glands, with their modifications. 
Certain of these glands play an important part in Mammals 
on account of their odoriferous secretions. In Man the secretion 
of the axillary and anal glands is well known to have a penetrating 
odour, but the significance of this we have so far failed to discover. 
NS 
RSS 
3 ~ SS 
Fic. 9.—DIAGRAMMATIC REPRESENTATIONS OF THE EARLY DEVELOPMENT OF THE 
LEADING TYPES OF MAMMARY GLANDS. (Modified from Gegenbaur. ) 
A, First or undifferentiated (mammary pit) stage ; B, stage of the false teat; C, stage 
of the true teat ; v. v., rim (or rampart) of the glandular area ; fg., glandular area ; 
gl., Mammary glands; d., mammary canal. 
The mammary glands, in all Mammals higher than the Mono- 
tremata,’ must be regarded as aggregates of much modified sebace- 
ous glands. This is attested not only by their whole structure, 
and by the nature of their secretion, but also by the fact that the 
sebaceous glands lying immediately around the teat in the female, 
the so-called Montgomery’s glands, grow larger when lactation 
begins, many of them yielding milk. This functional transition 
from sebaceous to mammary glands furnishes the best evidence for — 
their homology (Gegenbaur). In rare cases sebaceous glands still 
farther from the teat may also take part in lactation, instances being 
known in which such glands extended as far as the axillary region. 
These facts lead us to believe, & priort, that all parts of the 
skin may be capable of producing mammary glands. 
1 The mammary organ of the Monotremata is derived from sweat-glands, so that we 
have a diphyletic origin for the mammary glands collectively considered (Gegenbaur). 
