406 ON THE SENSITIVENESS OF THE SKIN TO LIGHT. 



ants in which side of the box they rested. Moreover, 

 every time the water and the cardboard were trans- 

 posed, the normal ants were much excited and began 

 running about to avoid the h'ght, while the hoodwinked 

 ants were quite unatFected. 



These experiences, therefore, proved that the varnish 

 did, in fact, render the ants temporarily blind, their 

 instincts being in other respects unaffected. 



He then replaced the cardboard and water by a 

 solution of esculine, which is impervious to the ultra- 

 violet rays, and a glass of deep cobalt, which stopped 

 most of the other rays but permitted the ultra-violet to 

 pass. The results then were : — 



Undee the Esculine. Under the Cobalt Glass. 



61 82 40 15 



Thus, then, a very large proportion of the normal 

 ants preferred to avoid the ultra-violet rays by going 

 under the esculine. To the varnished ants, on the 

 contrary, it was indifferent whether they were under 

 the esculine or the cobalt. The slight preponderance 

 in favour of the esculine was probably partly due to 

 having started the experiments with a larger number 

 of ants in the side of the box then covered with 

 esculine, and partly from the fact that the hoodwinked 

 ants would have a tendency to accompany the others. 



From these and other experiments M. Forel comes 

 to the same conclusion as I did, that the ants perceive 



