478 Mr. Poalton's/;t/-^/te;- experiments upon 



G. APPENDIX. 



An account of the various receptacles used in the edperi- 

 inents on p)upie. (C.) 



In the experiments upon pupae a great variety of 

 receptacles was employed. Inasmuch as the crowding 

 of the pupae greatly affects their colour, it is necessary to 

 give the approximate dimensions. A full description 

 will now be given, in which each receptacle will be 

 denominated by the number which represents it in 

 the experiments described in the paper. 



A. Black Surroundings. 



I. A low wide glass cylinder, 1'86 decimetres diameter, '91 high ; 

 lined inside with black tissue-paper (1 layer), and 2 laj^ers for roof. 



II. A very similar cylinder, 1-76 decimetres diameter, '77 high ; 

 lined with 1 and covered with 2 thicknesses of black tissue-paper ; 

 roof, 2 thicknesses. 



III. A very similar cylinder, 1'6 decimetres diameter, 1*0 high; 

 lined and covered as in II. 



These 3 cylinders were sometimes employed in strong light, 

 being placed on their sides, and the open end closed by a sheet of 

 clear glass. The upper part of the side then became the roof, and 

 the paper roof a black backgroiind. 



In other experiments they were used in darkness, being placed 

 on their open ends on a Hoor of black tissue-paper. In many cases 

 the darkness was rendered complete by a further covering of mats, 

 rugs, &c., although it was tolerably complete when these were 

 omitted. 



IV. A tall glass cylinder, '825 decimetres dinmeter, 1-79 high ; 

 lined inside for half the circumference with a single layer of black- 

 tissue paper ; roof, 2 layers of same. 



This was always used in strong light, the clear half of the 

 cylinder being turned towards the window. 



V. A similar cylinder, with the black background fixed outside 

 the glass, the roof consisting of a single layer of tissue-paper 

 gummed on to a sheet of glass, which was turned glass-downwards 

 on the open end of the cylinder. 



This was always used in strong light, and it was employed to 

 determine whether a black paper surface was as effective when 

 separated from the larvte by the thickness of the glass. 



VI. A similar arrangement, with a domed cylinder, like those 

 described below. 



VII. This was one out of three compartments in a wooden box, 

 measuring 3*3 decimetres high, 1"43 wide in front, l'S5 wide at 

 back, l'2y deep; lined throughoiit with black tissue-paper. 



A clear glass sheet closed the front, and this was always turned 

 towards a strong light. 



