16 Mn. B. F. OUMMIXGS OX 



Httmidity Experiments. 



In order dii'ectly to test Newts for a supposed faculty for 

 perception of humidity in the atmosphere, I planned apparatus to 

 work with electric fans driving two air currents which were to be 

 kept at an even temperature and velocity. One current was to 

 be thoroughly saturated by passage over a series of porous plates 

 containing water, and the other to be kept dry. The Newt 

 to be tested was to walk down an inclined runway, and to be 

 exposed on one side to the wet cuivrent and on the other to the dry. 

 At the bottom of the runway it was free to move in the direction 

 of either current. Fortunately for me, before carrying out this 

 elaborate apparatus in detail, I took the precaution of making a 

 few of what I considered would prove only preliminary trials 

 with a simpler arrangement in which the temperature factor was 

 not eliminated. I quickly formed the opinion either that Newts 

 were unable to detect moisture at a distance and slight variations 

 in temperature, or that my method of experimenting was un- 

 satisfactory. 



Although the existence of this faculty — which Romanes 

 favoured — seems improbable in the face of the facts recorded in the 

 two previous sections, an ingenious experimenter might perhaps 

 obtain more encouraging results. I think, though, such a per- 

 ceptive power in Newts would prove to be of too slight a nature 

 to be easily demonstrated by a laboratory experiment, and 

 especially by one such as mine, where a turn right or left at the 

 end of a runway, after a comparatively short exposure to the 

 conditions, was to decide each test. JT 



Discussion, 



The evideuoe preseuted, fragmentary as it is, lends support to 

 the hypothesis that Newts and presu.mably other Amphibia 

 possess a homing faculty. Table III, is interesting, particularly 

 that part dealing with the imported Newts, as one would have 

 been led to expect more of these to return if only by chance ; 

 for they were set loose at very short distances from the pond (with 

 one or two exceptions). But then the small size of the pond must 

 be remembered, particularly in comparing with the account in 

 Romanes' 'Animal Intelligence' where no mention of the size of 

 the pond concerned is given. It will be seen that more imported 

 Newts got back in 1911 than in 1910, This may be explained 

 by the fact that experiments in 1911 were begun earlier than 

 in 1910, when the Newts might have already done some 

 breeding before being C;aught. Their desire to find water would 

 then be proportionately less^ This qualification does not apply 

 to the natives, as the same natives were used several times over 

 and their breeding was therefore prevented up to May in both 

 years. Furthermore, in the experiments of 1911, the Newts, 

 both imported and native, were set loose, with one exception, 

 along t'bp iuf'line X. This incline was undoubtedly the most 



