the colours of certain Lvpidoptera. 



42^ 



This experiment thus confirms and extends the con- 

 chisions arrived at from the nse of the other form of 

 case, indicating that the Hght acts upon widely distri- 

 buted nerve terminations in the skin. 



The same experiment was also tried with another 

 kind of case. Strips of glass were glued on to a glass- 

 sheet in such a manner as to make compartments 

 9*6 centimetres high, 2'3 wide, and 1*6 deep below, 

 •3 deep above. Each row of compartments was closed 

 by a single glass front, thus forming a set of wedge- 

 shaped spaces tapering upwards in the position in 

 which the whole was placed (see Plate XV., Fig. 6). 

 The backs of half the compartments were lined with 

 white tissue paper, and the glass front with black, the 

 other half being treated in the converse manner. They 

 were placed in a strong light, the white surface being 

 in half the instances turned to the light and in half 

 turned away from it. 



The compartments tapered so that the larvae could not 

 reach the top, but suspended themselves somewhere 

 about the middle of either the back or front ; the white 

 spots on the black surfaces represented in fig. 6 are the 

 silken bosses. Hence the larval dorsal area was exposed 

 to one surface, while the ventral area was in contact with 

 the other, as in the last experiments, except that here the 

 conditions were more uniform in that each surface could 

 be turned towards the light. All the larvaB belonged to 

 one company captured near Oxford, and the pupae were 

 compared Aug. 9. The results are tabulated below: — 



EXPEEIJIENT 103. 



Degrees of Pupal Colour. 



White sur- 1 11 fixed to black surface away 

 faces turned from light 



towards light, 

 black away 

 from it. 



Black sur- 

 faces turned 

 towards light, 

 white away 

 from it. 



10 fixed to white surface to- 

 wards light 



3 unlixed or fell off ; position 

 uncertain 



19 fixed to black surface to- 

 wards light 



4 untixed, or having fallen off 

 white ; uncertain 



3 

 2 



11 

 1 \ 2 



TUANS. KNT. SOC. LOND. 1892. PAUT IV. (dEC.) 2 I 



