Adjustment of colour in varicus inqtx, etc. ^11 



3. P^XPERIMENTS UPON THE WiNTER PUP^ OF Pojnlio 



machaon. (Y. M.) 



In order to continue the experiments, begun upon the 

 summer pupse, I obtained from Germany, from the 31st 

 of August to the 2n(l of September, 1898, about 150 more 

 larvse, most of them young. 



A2:)paratus. 



In order to cope to some extent with the difficulty I had 

 in taking the larvae just at the right moment, owing to my 

 long daily absences from home, I provided two special 

 breeding-cages. These were made ofyV inch deal, each in two 

 compartments. Thus there were four compartments the 

 external dimensions of which were 16 inches in height, 12 

 inches in depth from front to back, and 8 inches in width. 

 The front of each cage was a sheet of glass, about 14 

 inches in width and 12 inches in height, as it started at 3 

 inches from the bottom ; it was vertically divided down 

 the middle by the thin deal partition between the two 

 compartments. The backs were of perforated zinc, corre- 

 sponding in size with the glass fronts, and the outer sides 

 were of deal containing the doors. The tops wore open, 

 but covered with woven material as stated below. The 

 framework of the top, and generally, was about an inch 

 wide, and there were many angles more or less shady, 

 vertical, and horizontal, where the parts of the framework 

 met at right angles. 



The compartments were covered internally as follows: — 

 The whole of the interior, except the glass front and the 

 perforated zinc backs, was covered with tissue-paper ; black 

 in the black compartment, white in the white compartment, 

 green in the green compartment, and about one-half orange 

 and one-half yellosv (the division being vertical) in the 

 orange-yellow compartment. The perforated zinc backs 

 and the open tops were covered with woven material, viz. 

 the black compartment with double black muslin (covered 

 with a slate), the white compartment with double white 

 calico, the green compartment witli threefold yellow-green 

 art muslin (fourfold on the top except for the hrassicai experi- 

 ment hereafter described when it was twofold), the orange- 

 yellow compartment with orange-yellow leno ; this leno, 

 instead of paper, being also used in some of the angles of 

 the framework. 



The fronts of the cages were placed within a few inches 



