364 SIB J. LUBBOCK ON ANTS, BEES, AND WASPS. 



The green glass cut off the high end down to wave-length 465, 

 and also the red to 616. 



The red glass cut off the high end down to wave-length 582. 



The violet glass cut off the orange and yellow from wave- 

 length 684 to 583, and a hand between wave-lengths 543 

 and 516. 



The purple glass cut off the high end down to wave-length 528. 



The solution of chromate of potash cut off the high end to 507. 



The saffron cut off the high end to about 473. 



Blue fluid cut off the low end to 516. 



Eed fluid cut off the high end to 596. 



In my previous experiments with colored spectra, the ants 

 carried the pupse out of the portion of the nest on which coloured 

 light was thrown and deposited them against the wall of the nest ; 

 or, if I arranged a nest of Formica fusca so that it was entirely in 

 the light, they carried them to one side or into one corner. It 

 seemed to me, therefore, that it would be interesting so to arrange 

 matters, that on quitting the spectrum, after passing through a 

 dark space, the ants should encounter not a solid obstacle, but a 

 barrier of light. With this object, I prepared some nests 12 

 inches long by 6 inches wide ; and Mr. Cottrell kindly arranged 

 for me at the Eoyal Institution on the 29th of June, by means of 

 the electric light, two spectra, which were thrown by two glass 

 prisms on to a table at an angle of about 45°. Each occupied 

 about 6 inches square, and there was a space of about 2 inches 

 between the red end of the one and the violet of the other, the 

 more distant spectrum being a good deal the brightest. 



Exp. 1. — In the light space I placed a nest of Formica fusca, 

 12 inches by 6, containing about 150 pupae, and arranged it so 

 that one end was distinctly beyond the limit of the violet visible 

 to us, and all but to the edge of the green given by thalline paper* 

 and the other just beyond the visible red. The pupae at first were 

 almost all in or beyond the violet, but were carried into the dark 

 space between the two spectra, the bright thalline band being 

 avoided, but some pupse being deposited in the red. 



Exp. 2. — I then tried the same experiment with a nest oiLasius 

 niger, in which there were many larvse as well as pupse. They were 

 all at the commencement at the blue end of the nearer spectrum. 



* If paper steeped in thalline ia placed in the ultra-violet portion of the 

 spectrum, it gives, with rays of a certain wave-length, a distinctly visible green 

 colour, which therefore constitutes a green band. 



