the colours of certain Lcpidoptcni. 



3B9 



A. Dark Surrodndings (in ad- 

 dition to the necessary 

 green leaves of the food- 

 plant) : — 



B. Green Surroundings : — 



C. Similar Surroundings in 

 DIM Light : — 



D. Similar Surroundings in 

 Darkness : — 



E. Transference Experi- 

 ments : — 



F. White Surroundings : — 



G. Surroundings of other 

 Colours : — 



Experiments. 



1. Natural: — I. Black twigs ; II., brown 



twigs ; III., IV. and V., reddish twigs 

 or stalks, becoming blackish ; VI., 

 brown leaves ; VII., red leaves, be- 

 coming blackish. 



2. Artijicial : — VIII. Black enamelled 



smooth twigs; IX., black enamelled 

 rough twigs. 



3. Dark SurroumliiKjs near the larva, hiit 



not actuallij ill contact: — X. Dark 

 twigs. 



1. A^rt«(/raZ;— XI., XII. andXIII. Green 



leaves and shoots of food-plant 

 {Popahrs nigra) ; XIV., leaves and 

 shoots of food-plant, with golden- 

 green twigs intermixed. 



2. Artificial: — XV. Green paper spills; 



XVI., dark green enamelled rough 

 twigs ; XVII., dark green enamelled 

 smooth twigs ; XVIII., light green 

 enamelled twigs. 



XIX. Dark twigs; XX., red stalks, be- 

 coming blackish ; XXI., green leaves 

 and shoots of food-plant; XXII., 

 dark twigs ; XXIII., green leaves 

 and shoots. 



XXIV. Dark twigs; XXV., green leaves 

 and shoots of food-plant. 



XXVI. Transferred from green to dark 

 surroundings ; XXVII. , transferred 

 from dark to green surroundings. 



XXVIII. White paper spills ; XXIX. and 

 XXX., white enamelled twigs. 



XXXI. Dark blue paper spills ; XXXII. , 

 blue spills ; XXXIII., orange spills 

 and pieces of paper ; XXXIV., 

 orange enamelled twigs. 



During the critical period of all these 34 experiments 

 the same food was made use of — the leaves of the black 

 poplar {Pojmlus nigra). Great care was taken to ensure 

 that the larva3 were supplied with leaves of the same age, 

 and it may be safely concluded that no effects were pro- 

 duced by the different condition of the food-plant in the 

 various experiments. 



The conditions described above were kept up in all 

 cases until August 3rd, when the larvie were packed for 

 removal to Edinburgh, in order that they might be ex- 

 hibited at the British Association. After this date they 

 were fed irregularly, and sometimes upon other food- 

 plants, while the conditions of some of the experiments 

 were relaxed ; but only in the case of larvfe which were 

 advanced in the last stage, and long past the period at 



