1887.] between certain Pupce and their Surroundings, 97 



produced by the use of white surroundings. The totals obtained by 

 the use of these different surroundings were as follows (omitting the 

 orange). 



Degrees of colour. 



(1.) 



(2.) 



Dark 

 (3.) 



(3.) 



Light 

 (3.) 



(4-) 



(5.) 







2 



8 





25 





1 



3 



= 39 



Black „ 



11 



29 



27 



22 



14 



2 





= 105 



White „ 





7 



21 



37 



44 



25 



11 



, =145 



Gilt „ 





1 



2 



7 



16 



27 



14 



= 67 



















356 



2. The Colours of Wild Pupce. — It is impossible to realise the 

 extremely remarkable results of the gilt and white surroundings 

 without taking into account the fact that a (4) or a (5) is very rarely 

 seen in the field, except when the pupa is diseased. Out of fifteen 

 wild pupae found August 31 on a grey stone wall, the lightest pupae 

 were (3), while there were four of the degree represented by (1), and 

 there was only the minutest spot of gold to be seen after careful exami- 

 nation on two of the pupae, and none on any of the others. 



3. The Effects of Mutual Proximity. — Inasmuch as the above 

 figures show that the larvae are sensitive to dark surfaces and the 

 larvae themselves are almost black, it appeared probable that they 

 would be mutually influenced when a large number pupated in close 

 proximity. This was incidentally shown to be the case in several of 

 the experiments, of which the most striking was as follows. Four 

 larvae were placed each in a separate cylinder while twelve were placed 

 together in another similar cylinder, all having the same conditions of 

 light and each cylinder lined and roofed with an equal amount of 

 white paper and each standing upon an opal glass floor. Of the twelve 

 larvae ten pupated in close proximity upon the roof and sides, and were 

 all light (3), while the remaining two pupated on the floor and were 

 both (4). Of the four pupae in separate cylinders two were (4) and 

 two were (5). In consequence of these and other equally con vincing 

 results the exact position of the pupae has to be taken into account in 

 estimating the influences which have been at work, and in all the most 

 careful experiments only one or two larvae were placed in each coloured 

 case. 



4. The Effects of Illumination. — One experiment was directed 

 towards the comparison of the influence of a black surface in strong- 

 light and the same surface in darkness, and the results show clearly 



h 2 



