1100 The American Naturalist. [December, 
is principally to furnish oxygen and the aquatic part to’ eliminate 
carbon dioxide” (Wilder, ’77; Gage, S. H. and S. P., ’85, ’86,. 
88; Mark, ’90). 
It has been found in every one of a great many cases that 
whenever the respiration is wholly aérial, the entire mouth cavity 
is lined with ciliated epithelium which is directly continuous with 
the ciliated epithelium of the cesophagus. This is found not 
_ only in the red forms and the viridescent forms that had not yet 
entered the water, but when an aquatic form was kept in the air 
for ten days or two weeks the epithelium of the mouth was like- 
wise found: to be ciliated like that of the proper aérial forms. 
This was verified on several specimens and direct comparisons 
made with specimens from the same aquarium. 
The branchiate larvæ and the adult aquatic forms have an oral 
epithelium of non-ciliated cells, as in Necturus and Crypto- 
branchus. It is astonishing to see how quickly a Diemyctylus 
with purely aérial respiration and ciliated oral epithelium will 
assume a partially aquatic or mixed respiration and the ciliated 
epithelium of the mouth become non-ciliated. The change has 
something of the character and certainty of a simple chemical 
reaction, and appears to show the direct relation of the mode of 
respiration to the character of the oral epithelium. 
2 To determine whether or not the mouth has a lining of ciliated epithelium, the 
nd the 
ciliated epithelium, for the ciliary currents quickly sw t clots toward and 
finally into the stomach. It - asa an excellent method for discovering small ciliated 
areas. In addition to this yade of the epithelium 

arious parts of the mouth. This, of course, hat to to be. the method employed in 
fro! 
determining the character of the oral epithelium at the beginning of an experiment with 
iving specimens, In the scrapings from the mouth of an aquatic Diemyctylus a few 
ciliated cells may be found under the microscope, but in such specimens penn 
no demonstrable ciliary currents. The source of the few cells is thought to 
the opening of the glottis or from the ciliated lining of the mouths of the buccal phar 

ohh a a PR SER CHR irae 

