340 Mr. Vonlton's farther experiments upon 



which change of colour is possible. Whenever there 

 was any possibility of furtlier change, the conditions 

 were carefully adhered to. 



The majority of the larvae were also arranged in cases 

 more suitable for travelling than those in which they 

 had been previously kept. During the susceptible stages 

 clear glass vessels were always employed ; some of these 

 were cylindrical, others of the shape shown in Plate 

 XV., fig. 4, bulging in part of the length and con- 

 tracted at both ends, although often to an unequal 

 extent, while the bulging was nearly always closer 

 to one end than the other. These will be called 

 lamp-shades in the description of the experiments, and 

 their heights and approximate capacities will also be 

 given. The former will be called cylinders, and their 

 heights, internal diameters, and approximate capacities 

 will also be furnished. Each glass receptacle was placed 

 on a plate perforated by a hole, through which the stalks 

 of the food-plant passed into water below. The food- 

 plant was invariably represented by green leaves and 

 shoots alone, whether other surroundings were made use 

 of or not. 



The details of the experiments will now be given iu 

 order. 



A. Dark Surroundings. 

 (In addition to the necessary green leaves of the food- 

 plant). 



1. Dark Objects ivliich arc natural to the Larvce. 

 (See Table, pages 342, 343, and 344.) 



The results of these experiments are a great advance 

 upon those of 188D. Instead of merely proving that 

 dark larvie are produced by dark surroundings, we now 

 know that each of certain varied tints which are liable 

 to occur in a dark environment produces its appropriate 

 effect. 



Thus black twigs produce black larvae (I. and fig. 10) ; 

 brown twigs produce brown larvte (II. and figs. 11 and 

 12) ; light brown mottled leaves i)roduce larvs which 

 harmonise with them (VI. and fig. 14). 



I omit Experiments III., IV., V , and VII., because 

 the results were complicated by the environments altering 



