SIR JOHN LUBBOCK ON ANTS, BEES, AND WASPS. 



123 



&c., were able to perceives light of different wave-lengths, 

 and that their eyes were sensitive to the ultra-violet rays 

 much beyond our limits of vision. His observations do not in 

 any way controvert these deductions : indeed the argument by 

 which (p. 234) he endeavours to prove that the effect is due 

 to true light and not to warmth, presupposes that sensations 

 which can be felt by the general surface of the skin are still 

 more vividly perceived by the special organs of vision. 



Prof. Graber's observations have been followed up by 

 M. Forel *. He took fifteen specimens of Cmnpo7iotus ligni- 

 perdus^ which is a large species and, moreover, possesses the 

 advantage, for this purpose, of having no ocelli, and carefully 

 covered the eyes with opaque varnish. He then placed them in 

 a box with ten normal specimens of the same species (to which 

 he subsequently added five more), and covered over one half of 

 the box with cardboard and the other half with a layer of water. 

 In this way the one half of the box was darker than the other, 

 but the temperature of the two sides was approxnnately equal. 

 In four experiments the numbers were as follows : — 



Under the cardboard. Under the water. 



Hoodwinked Ants. Normal Ants. Hoodwinked Ants. Normal Ants. 

 3 9 12 1 

 13 7 3 3 

 9 9 5 1 

 3 8 12 2 



28 33 32 7 



It will be seen that a very large majority of the normal ants in 

 every case went under tlie cardboard; while it was practically 

 indifferent to the hoodwinked ants in which side of the box they 

 rested. Moreover, every time the water and the cardboard were 

 transposed, the normal ants were much excited and began run- 

 ning about to avoid the light, while the hoodwinked ants were 

 quite unaflected. 



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 w^ater by a solution of 



* Rc>c. Zool. Suisse, 1887. 



