LIFE HISTORY OF DESMOGNATHUS FUSCA. 299 



rapidly up its side, and attempt to make their escape, while in 

 shallow water they remain for days in an open dish and make 

 no such attempt. This adjustment to shallow water is un- 

 doubtedly a means for insuring that they remain in regions where 

 at the time of metamorphosis they can reach the necessary 

 terrestrial environment; for the adults, being lungless, have no 

 hydrostatic organs, neither have they any method of aquatic 

 respiration other than the skin. 



The larvae react vigorously to attempts to capture them by 

 any seizing act or any method which involves pressure against 

 the opposite sides of the body, being evidently organized to escape 

 from jaws and teeth. That they frequently barely succeed in 

 making such escapes is evidenced by the large proportion of 

 maimed individuals which one finds, tails and hind legs being 

 the parts most frequently lost. The location of the lateral line 

 organs or neuromasts upon opposite sides along the lateral 

 surfaces of the body may have some significance in connection 

 with this reaction. On the other hand, the larvae do not appear 

 to be especially sensitive to mere tactile stimuli even when these 

 are applied to the regions where the neuromasts are most abun- 

 dant, unless such stimuli are applied upon two opposing regions. 

 After the application of such opposing stimuli, however, or the 

 repeated application of single stimuli, the sensitiveness of the 

 larva to touch seems to be for a time considerably augmented, 

 and a stimulus applied to a single region will then give rise to 

 vigorous efforts to escape. 



On the other hand the larvae appear to have no reflex mechan- 

 ism for protection against forces which gently raise and lower 

 the body, like the slight natural movements of quiet water. 

 They may therefore be readily captured by lifting them with the 

 hand, a watch glass, or any other concave object which may be 

 passed gently under them and then quietly raised; the gradual 

 flowing of the water from the surface upon which they are thus 

 lifted produces also no disturbance so long as the larva remains 

 moist. Larvae may in this way be transferred from their natural 

 habitat to the collecting jar, without a single movement on their 

 part, while the slightest pinching or seizing force results almost 

 invariably in such violent wriggling that the animal makes its 

 escape. 



