292 THE WONDERS OF INSTINCT 



that our ingenuity, lavish of time and patience, has been 

 able to obtain from the original plant since the most 

 distant ages. 



But what did the caterpillar eat before our cabbages 

 supplied him with copious provender? Obviously the 

 Pieris did not wait for the advent of man and his horti- 

 cultural works in order to take part in the joys of life. 

 She lived without us and would have continued to live 

 without us. A Butterfly's existence is not subject to 

 ours, but rightfully independent of our aid. 



Before the white-heart, the cauliflower, the savoy and 

 the others were invented, the Pieris' caterpillar certainly 

 did not lack food: he browsed on the wild cabbage of 

 the cliffs, the parent of the latter-day wealth; but, as 

 this plant is not widely distributed and is, in any case, 

 limited to certain maritime regions, the welfare of the 

 Butterfly, whether on plain or hill, demanded a more 

 luxuriant and more common plant for pasturage. This 

 plant was apparently one of the Cruci ferae, more or less 

 seasoned with sulphuretted essence, like the cabbages. 

 Let us experiment on these lines. 



I rear the Pieris' caterpillars from the egg upwards 

 on the wall-rocket (Diplotaxis tenuifolia, Dec.), which 

 imbibes strong spices along the edge of the paths and at 

 the foot of the walls. Penned in a large wire-gauze 

 bell-cage, they accept this provender without demur; 

 they nibble it with the same appetite as if it were cabbage ; 

 and they end by producing chrysalids and Butterflies. 

 The change of fare causes not the least trouble. 



I am equally successful with other crucifers of a less 



