NOTES ON THE COLOURING MATTER OF APHIDES. 171 



Mr. Sorby marks these stages of oxydation by the 

 production of four substances, viz. Aphideine, Aphidi- 

 luteine, Aphidiluteoline,and Aphidirhodeine; but before 

 these can be said to be distinct chemical principles, 

 or can have formula3 assigned to them, a further 

 examination is required. The cause of the varying 

 golden spring and autumn tints of our own woods, 

 and perhaps the still more pronounced colours 

 of the forests of America, is worthy of research, and it 

 is believed that Aphis changes, dependent on seasons, 

 have something in common with such phenomena. 



