this experiment is that all those that hatched were cripples. As I 

 mentioned above, only a few urticce were crippled, so that the result 

 is even more remarkable. This shows, I think, pretty clearly, that 

 such experiments as these in a more extensive form, both in 

 reagents and species, may lead to some developments which will 

 teach us more of the causes that lead to variation. 



Carbon Bisulphide. 



V. urticce. 

 Total number. Hatched. Cripples. Died. 



121 2 i 119, or 98 per cent. 



This gas is the most poisonous that I have ever used for urticce. 

 The two that emerged came out in the first twenty-four hours after 

 the pupae were placed in the jar ; so that one may consider that this 

 sulphur compound is absolutely fatal to this species. No A. grossu- 

 lariata were experimented on with this gas. 



Control. 

 V. urticce. 



Total number. Hatched. Cripples. Died. 



106 55 20 51, or 48 per cent. 



The large number of this species dying in pupae and the high 

 percentage of cripples was in part no doubt due to bad packing in 

 forwarding them to me by post. Nothing worthy of note occurred in 

 colours on wings. 



A. grossulariata. 

 Total number. Hatched. Cripples. Died. 



125 88 4 37, or 29 per cent. 



These gave a fair average of emergences, and you will see in the 

 box that no specially dark forms occur. 



This ends the record of the experiments ; but before finishing 

 this paper I should like to say that in this record no mention has 

 been made of 600 Anthrocera filipendulce pupae that I also placed in 

 precisely similar conditions to those given above, the reason for the 

 omission being that only about a dozen hatched, and of these only 

 three were perfect. Out of the nitric acid jar one yellow var. 

 emerged, but this was a cripple. 



On looking over these results the two points that strike one are 

 the high death-rate, and the pigmentary changes in the wings. 



The death-rate among the urticce is especially noticeable where 

 they were exposed to continuous high temperature, hydrogen 

 sulphide and bi-sulphide of carbon, the latter being particularly 

 deadly. 



