124 



SIE JOHN LUBBOCK OlST ATJTS, BEES, AND WASPS. 



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 : — 



Under the Esculine. Under the Cobalt glass. 







XiUULlVVlllllCvl iXilto. 





11 



8 



8 



1 



11 



13 



4 



2 



9 



12 



5 



3 



5 



13 



9 



2 



10 



12 



4 



3 





11 



12 



3 



12 



13 



3 



1 



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 tlie contrary, it was indifferent whether 

 they were under the esculine or the cobalt. The slight prepond- 

 erance 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. 



Prom these and other experiments M. Torel comes to the same 

 conclusion as I did, that the ants perceive the ultra-violet rays 

 with their eyes ; and not, as suggested by Graber, by the skin 

 generally. 



Experiments with JPlatyarthrus. 



In connection with this subject I may add that I do not at all 

 doubt the sensitiveness to light of eyeless animals. In experi- 

 menting on this subject I have always found that though the 

 Flatyariliriis, which live with the ants, have no eyes, yet if part 

 of the nest be uncovered and part kept dark, they soon find 

 their way into the shaded part. It is, however, easy to imagine 

 that in unpigmented animals, whose skins are more or less semi- 

 transparent, the light might act directly on the nervous system, 

 even though it could not produce anything which could be called 

 vision. 



