338 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
mm. 
means of the skin, as was thought to be true in the case of the frog and 
axolotl by W. F. Edwards and Paul Bert; or, second, almost entirely 
by means of the anterior portion of the alimentary canal, mouth and 
pharynx, as Camerano maintained in the case of Spelerpes juscus and 
Salamandrina perspicillata ; or, third, by a combination in equal meas¬ 
ure of these two methods; or, fourth, by 
means of the added help of some other part 
of the body ? 
I shall describe the experiments which I 
devised, dividing them into two groups: 
first, those made with freshly removed 
pieces of integument, experiments on the 
osmotic power of the skin; and second, 
experiments on the living animal. 
In order to test the permeability of the 
skin of lungless salamanders as compared 
with the skin of lunged forms, a series of four 
osmometers was set up as follows. The 
apparatus is shown in fig. A; to a simple 
iron chemical stand (st.) was attached an 
upright millimeter scale (mm.), with a glass 
tube (t.) firmly wired to it. A shorter glass 
tube of slightly larger diameter (/'.) was 
then covered at one end by a sufficiently 
large piece of amphibian integument (i.), 
removed from the underlying connective 
tissue and muscles of a freshly killed 
animal. This bit of integument was tied 
Fig. a.— mm., millimeter scale; p rm }y ; n p} ace by means of a thread. The 
i., piece of integument; j., J ^ 
joint made with rubber tub- small tube was then filled with a solution 
mg and wire; sol sugar soiu- SU g ar water three parts, sugar one 
tion; st., stand; t., glass tube; & . 1 ’ b 
t'., shorter glass tube; w., part, and jointed firmly to the longer glass 
glass tumbler filled with dis- ^be a bove by means of rubber tubing and 
tilled water. J & 
wire (j.). The smaller tube was then 
immersed in a tumbler of distilled water so that the fluids, inside 
and out, stood at the same level. A bit of thymol, dropped into the 
water in the tumbler, prevented maceration of the skin during the 
time that the experiments were set up. The four skins used for 
these experiments were those of Desmognathus Jusca, a lungless form; 
