AMPHIBIAN MIORATIOX. 9 



yards from their habitual haunts, returneil to theui again and 

 again. He also expressed the opinion that Frogs were able 

 to pei'ceive moisture from a great distance, and he quotes Warden 

 who in " An Account of the United States," vol. ii. p. 9, says 

 that a pond containing some Frogs having dried up, the animals 

 "made sti'aight for" the nearest water, though it was eight 

 kilometres away. 



(JOMPEXSATORY HeAU-MOVEMENTS. 



In all experiments with the Amphibia it is necessary to bewai-e of 

 en-or thi-ough compensatory head-movements, which, if neglected, 

 give a false complexion to the results. No mention of them is 

 made by Romanes' correspondents and no details of the experi- 

 ments are given. It is astonishing to find how jiersistently Newts 

 will return and immediately re-enter their pond, after they have 

 been removed from it to some considerable distance. Even when 

 placed heading directly away from the water, they turn round and 

 walk towai'ds the water, as if endowed with a, quite uncanny 

 knowledge of the geographical features of the neighbourhood of 

 their breeding-pond. The explanation partly lies in the head- 

 movements contrary to the movement of rotation, set iip by the 

 motion of the experimenter's hand as he turns the Newt round 

 to face away from the water. The Newt mechanically responds 

 by turning round, with the head towards the water. These move- 

 ments are very pronounced in the Newt on account of its linear 

 shape. A Newt, on a rotating disc whicli is being moved back- 

 wards and forwards through an angle of 180°, responds correctly 

 if the motion is slow, i. e., it turns its head regularly in the 

 opposite direction to the backward and forward movements of the 

 disc. If the motion of the disc be fast, it overtakes the slow 

 head-movements of the Newt, and the Newt becomes confused and 

 escapes from the predicament by lowering its chin so as to place 

 it in contact with the moving disc. No response is then given. 

 Continuous rotation in one direction produces no very marked 

 external signs of giddiness. But in the Common Toad {Bufo 

 vulgaris) these signs are marked. While the disc is moving the 

 head is motionless. As soon as it stops, the Toad begins to ci-awl 

 x-ound in circles moving in the direction the disc had been moving. 

 One of these animals, after rotation of one minute, in this way 

 crawled through four circles ! If a Newt be rotated through 90° 

 in a trough with perpendicular walls two inches high, I have seen 

 it turn in response to the rotation and climb over the side. 



Geotaxis. 



This subject must also be taken into consideration. It must 

 be borne in mind that the ground around most ponds is sloping. 

 Most fresh water lies at the bottom of hollows or at the foot of 

 sloi)es. Newts are positi\-ely geotactic. They preferred to walk 



