SEELYE: CIRCULATORY SYSTEM OF DESMOGNATHUS. 337 
inner surface of this cutis is found a firm layer, with the appearance in 
the sections of many fine undulating lines parallel to the surface {cut. 
has.), which I have called the basement layer of the cutis. Between 
this and the epidermis, among loose connective tissue and lymph 
spaces, lie the slime glands {si. gl.), flask-shaped, with long delicate 
necks or ducts, passing out through the epidermis and cuticula to ex¬ 
ternal openings {ex. op.) on the surface. The cuticula lines the outer 
ends of the ducts. These slime glands are made up of a single layer 
of cells arranged around a hollow center. Also in the cutis and around 
and between the glands are found the capillaries {cap.) previously ob¬ 
served in a surface view of the skin, and the pigment bodies {pig-) 
already mentioned, lying between and beneath the capillaries. The 
capillaries are now seen to lie directly underneath the epidermis, some¬ 
times pushing up against its inner boundary so as to make the epider¬ 
mis slightly thinner in those regions. 
A comparative examination was made of the skins of other sala¬ 
manders: one with rudimentary lungs, Amblystoma opacum, and sev¬ 
eral lunged forms, Salamandra maculosa, Triton alpestris, Diemyc- 
tylus viridescens, and Ambly stoma punctatum. The only point that 
seemed to hold constant as a difference between the integument of 
lunged and lungless forms was that the thick layer of wavy-lined 
appearance on the inner surface of the cutis, basement layer of the 
cutis (pi. 26, figs. 7 and 8, cut. bas.), was much thicker in lungless 
forms. In some curious way this seems to be correlated with the 
lungless condition. Beneath the basement layer of the cutis, blood 
vessels are found in the connective tissue and between the muscles 
(pi. 26, fig. 7, cap. sub. cut.), but these are not nearly as numerous 
as the subepidermal capillaries. 
Physiological Experiments. 
An excellent summary of what has been done by previous investiga¬ 
tors along the lines of experimentation for determining the respiratory 
functions of different areas of the amphibian body, is given in the arti¬ 
cle by Emil Bethge (’98). 
The problem which I sought to solve by a series of experiments was 
as follows. Does Desmognathus fusca, or in general do lungless sala¬ 
manders obtain oxygen and give off carbonic acid gas, first, chiefly by 
