INTEGUMENT OF NECTURUS MACULOSUS 539. 
or black. Esterly (04) reports that, in Plethodon, Tiinzers 
orcein, another elastin stain, colors the cytoplasm of the mucous 
gland a deep brown. 
The foregoing observations prove beyond a doubt that, at 
least in the mature stages we are dealing with, two distinct 
kinds of glands, granular and mucous, exist. The granular or 
poison glands are larger than the mucous glands and appear more 
distended. While there is a well-developed muscular layer 
enveloping the granular glands, none is ever found on those of 
the mucous type. The nuclei of the granular cells are large and 
rounded and stain as do the nuclei of ordinary epidermal cells. 
The nuclei of the mucous cells, on the other hand, are irregularly 
flattened and stain intensely in all basic stains. Further, the 
granular secretion is very readily colored in all plasma stains, 
but is untouched by nuclear stains. In contrast with this, the 
secretion of the mucous glands, while it stains well in Dela- 
field’s or Ehrlich’s haematoxylin and in thionin or Weigert’s 
resorcin-fushsin, is not affected by ordinary plasma stains. It 
is also never found in the form of granules. 
3. Development. a. In other Amphibia. With one exception, 
Phisalix (’00 a-e, ’03), all writers are agreed that the glands have 
an ectodermal origin and develop from the epidermis. Nicoglu 
(93) and Heidenhain (’93) concluded, from their observations 
on the relation between the intercalary region of the glands and 
the epidermis in Triton, that the glands must be formed by an 
invagination from the malpighian layer. Maurer (’95) showed 
that in Salamandra, Triton, and the frog, the glands have this 
origin, appearing within the epidermis as a compact mass of 
round cells with an irregu’ar arrangement. The cells multiply 
by indirect division and later push down into the dermis. Junius 
(96) confirms for the frog Maurer’s description of their develop- 
ment. 
According to Phisalix, however, the glands of the salamander 
are of mesodermal origin. They develop from cells in the dermis 
which multiply mitotically and acquire a union with the epi- 
dermis. Ancel (’02) has followed closely the development of 
the glands in Salamandra, Triton, Alytes, Siren, and Amphiuma. 
