262 FROGS, TOADS, AND NEWTS [CH. VIII 



is effected through it without the active intervention 

 of any muscular apparatus. Indeed during hibernation 

 the skin alone is sufficient for all respiratory needs, thanks 

 to the copious supply of blood brought to it by the 

 cutaneous branch of the pulmo-cutaneous artery. During 

 the periods of normal activity, however, the respiratory 

 movements are very evident. These consist of rapid 

 superficial oscillations of the throat, interrupted by oc- 

 casional more profound movements affecting the ventral 

 surface and flanks of the body. The up-and-down move- 

 ments of the throat take place while the glottis (the 

 entry to the passage leading to the Jungs) is closed, and 

 are only accompanied by slight movements of the nostrils, 

 which are for the most part open; they have no direct 

 connexion with the pulmonary respiration. Mascacci and 

 Camerano have shown that an interchange of gases takes 

 place through the mucous membrane of the mouth, and 

 that this is quite as important a respiratory organ as the 

 skin 1 . The "latter of these two observers finds that in 

 certain lungless amphibians, e.g. Spelerpes fuscus and 

 Salamandrina perspicibata, buccal respiration has entirely 

 replaced pulmonary, while the cutaneous interchange is 

 quite unimportant; and in these forms the oscillations of 

 the throat are particularly well marked. It is probable 

 that the peculiar arrangement of the capillary blood 

 vessels of the mucous membrane of the mouth and 

 anterior part of the oesophagus is intimately connected 

 with this method of breathing. Langer and Schobl have 

 described these capillaries in the frog as arranged in a 

 1 Cf. Howes, Jour. Anat. and Pliys. xxm. 



