the colours of certain Lepidoptcra. 393 



in such a form that the larvre would be exposed to con- 

 flictmg stimuli during the most sensitive stage (II.) > as 

 well as the last. 



With this object in view, I constructed the case 

 which is represented, about one-fifth of the true size, 

 in Plate XV., fig. 5. It consisted of three rows of 

 compartments, each row containing 14. The com- 

 partments were 8*1 cm. high in the two upper rows, 

 rather higher in the lowest row. Their width varied 

 from 1*5 to 5*0 cm. ; their depth was 1'2 cm. at the 

 bottom, while above it tapered away to a chink only 

 0*3 cm. wide. The front of each row was covered in by 

 a strip of clear glass, which sloped gently backwards, 

 resting upon the wedge-shaped divisions between the 

 compartments. These divisions and the backs of the 

 compartments were lined with alternating strips of gilt 

 (polished Dutch metal) and black paper (black tissue 

 paper). Those of the lowest row were crossed by two 

 narrow gilt strips, 0'8 cm. broad, separated by black 

 bands of three times the breadth, the uppermost being 

 rather broader, and the narrow roof and floor (about 

 1'2 cm. wide) being gilt. The compartments of the two 

 upper rows were crossed by strips of black and gilt, with 

 an equal breadth of about 1*5 cm., except the uppermost 

 (black in the top row, gilt in the middle one), which was 

 rather broader. The narrow roof and floor were opposite 

 in colour to the adjacent strips. 



In use, the case was kept vertical in the position shown 

 in fig. 5, and a single larva, having ceased to feed, was 

 introduced into each compartment. Hence no allowance 

 has to be made for crowding. The larvte were left un- 

 disturbed in the compartments, and, after their first 

 excitement, passed all the stages in a normal manner, 

 and formed pupse, suspended to either the back of the 

 compartments or the glass front. It is clear that two 

 or more parts of the larval body, succeeding each other 

 antero-posteriorly, had been subjected to conflicting im- 

 pulses during the whole of the sensitive period. 



The last larvae of a company found towards the end of 

 August at Oxford, being mature, were at once placed 

 in the case just described. The pupae were compared 

 August 28, with the following results : — 



TRANS. ENT. SOC. LOND. 1892. — PAET IV. (DEC.) 2 G 



