56 A. B. MACALLUM. 
has pointed out this fact, and although he observed the passage 
of fibrils through the corium and their connection with the 
figures of Eberth, yet he was unable to form any opinion of 
the significance of either. 
Mitrophanow,! by employing the ordinary method of using 
gold chloride, and comparing its results with those obtained by 
Pfitzner’s method, came to the conclusion that in each of the 
two methods gold chloride selects entirely different tissue 
elements; that in the first nerve structures are stained deeply 
while the figures of Eberth remain uncoloured, and in the second 
method the chromic acid changes the chemical relations of the 
figures of Eberth in such a way that the latter become capable 
of impregnation with gold. He pointed out also that these 
structures are never so regular as Pfitzner has represented them, 
and that they are in no way connected with the fibrils which 
pass vertically through the corium, and which, in his opinion, 
are of connective-tissue origin. He found the coarser nerve- 
fibres of the skin arranged, as Hensen and Eberth described, 
in a plexus under the corium, and giving origin to fibrils which 
pass through that membrane to terminate between, but never 
within, the cells of the epithelium. With Pfitzner’s methods 
he was unable to find any intercellular terminations. 
IIl.—Materiat. 
My researches were carried on with the tadpoles of Rana 
halecina. These measured from two to two and a half inches 
in length, and several of them presented quite distinctly the 
outlines of the posterior limbs. In order to get characteristic 
preparations of the epithelium I found it necessary to keep the 
tadpoles in perfectly normal conditions, i.e. in water regularly 
renewed, and of a constant temperature. With the water 
unchanged for several days, or with its temperature consider- 
ably lowered for an equal length of time, the number of layers 
in the epithelium was found reduced to two, which apparently 
soon increased to three, four, and even five if the tadpole was 
again subjected to normal conditions. This reduction in the 
1 ¢Arch. fir Anat. und Phys.,’ Phys. Abth., 1884, p. 191. 
