vol. i.i Hubbard. — Protective Devices m Salamanders. 165 



experiments made the interpretation of I he results doubtful, and, 

 besides, did not fully answer the question whether under natural 

 conditions the salamander is really protected by its poison. 



After having tried the Diadophis, to see if it was hungrj . bj 

 giving it a Batrachoseps, I waited a das and then introduced a 

 swollen-tailed Pletliodon into the terrarium with the snake. The 

 snake was hungry and a series of encounters ensued. Three times 

 the Diadophis had the Plethodon by the neck and would surely 

 have disposed of it had I not beaten off the snake in order to give 

 the Plethodon every chance to save itself. Three times the 

 Diadophis seized the Plethodon round the middle and worked 

 toward the caudal end of the body. Then each time, but not 

 until then, the salamander poured out the milky secretion on its 

 tail and the snake released its hold. Upon the fourth attack of 

 this kind the Pletliodon dropped its tail and wriggled away, only 

 to lose the battle, for then the Diadophis devoured it tail and 

 all, not however without some gagging afterwards. 



The next morning, the Diadophis being in the same condition 

 of hunger as on the day before, I put with it another Plethodon. 

 As it crawled up upon the snake's coils, the latter became 

 aroused and glided toward the salamander, its tongue darting 

 out and in. The Plethodon, which had been perfectly motion- 

 less for some time, suddenly, without moving the rest of the 

 body, raised its tail and with a sidewise motion struck the 

 Diadophis squarely in the face. Somewhat daunted by this 

 reception the enemy retreated, but in a moment or two came up 

 again, this time from behind. When the snake's mouth was very 

 near, the salamander, rigid in every other part of its body, sud- 

 denly raised its tail, as a cat arches its back at a worrying dog. 

 At the same time the tail became covered with the milky fluid. 

 Diadophis, making a brief survey, retreated again, and the 

 Plethodon, after remaining motionless in this position for several 

 minutes, long enough for me to make a sketch from which fig. 6, 

 PI. XVI, was drawn, gradually lowered its tail until it rested on 

 the floor. The snake did not approach the salamander again. 



It would be rash in most instances to draw conclusions from 

 a single case or a single experiment, but there may be times when 

 that single case or that oue experiment is sufficient to determine 



