276 THE SALAMANDER 



excited, or moving, or is fatigued through being handled, the interval 



becomes much shorter. 



The complicated movements carried out to effect the filling and 

 emptying of the lungs are as follows. The depression of the mouth- 

 floor is exaggerated and prolonged. The 

 external nares are open during the first 

 part of this act and the air is drawn into 

 the mouth. This process is known as 

 aspiration. Just as the mouth-floor is ap- 

 proaching its lowest point the nares are 

 closed, or nearly so, so that the residue of 

 air is drawn from the lungs and mixed 

 with the pure air already in the mouth. 

 This process is called expiration. The 

 mouth-floor then rises and, the nares re- 

 maining closed, the mixed air is forced 

 into the lungs. This constitutes the act 

 £)iagram of the ^^ inspiration. The nares then open again 

 respiratory movements of the and there follows a longer or shorter 

 Salamander, comprising the clo- period of bucco-pharyngeal respiration 

 sure of the nares (upper line), the before this more complicated process of 

 rTTracinS'^'n^The'^T P^^^'^^U respiration is repeated. 

 moTrVpreTure\w^ To summarize: it seems that in all 



(After Willem.) Urodeles devoid of gills, the bucco- 



I. Commencement of pharynx is the region which is chiefly 

 aspiration. 2. Opening of concerned in the gaseous interchange 

 the glottis and the commence- ^^tween the blood and the air, to which 

 ment of the closure ot the , , • 11 /• 1 r 1 • 1 



nares. 3. The nares com- the skm and lungs (m those forms which 

 pletely closed. 4. Closure possess them) are subsidiary. In support 

 of the glottis. 5. Com- of this it should be noted that the whole 

 mencement of the opening of of the mouth and throat is richly vascular, 

 while Bethge has observed that the capil- 

 laries of this region approach very close 

 to the surface, actually pushing into the epithelial layer, between 

 the cells. 



2 4 



Text-Fig. 3. 



the nares. 6. 



completely open. 



The 



BIBLIOGRAPHY OF SECTION VIII 

 90, 91, 98, 99, 143, 144, 145, 146, 218, 233, 256, 259, 275, 293, 299, 391, 

 392, 437> 438, 452, 4975 498, 520, 554, 555, 737, 79^, 797, 801. 



