90 THE CANADIAN ENTOMOLOGIST. 



I do not know of any recorded instance where the larvae of the countless- 

 numbers of our Lepidoptera possess a similar faculty. Indeed, had such 

 a case been observed, especially in a single individual of any of the above 

 genera, I should assuredly have characterized it as one where the animal 

 possessed the power of altering its color, in accordance with the dictates 

 of a " will principle," whereby its protection was secured. This power 

 of adaptation to the colors of the insects' natural food, being protective 

 in its character, would be preserved, and thus, in the course of time, all 

 the individuals of the species would adopt it. 



But I am satisfied that the will (for assuredly these humble forms of 

 animal life are endowed with a small degree of it) has noticing to do with 

 these color transformations, but aver that they are due to the effects of a 

 changed nutrition, as specimens, as above asserted, were observed exhi- 

 biting the transitional stages. 



It has been shown by a French experimenter, according to the 

 Chroniqiie de la Society cT Acdijnatafion, that by feeding silk-v/orms on the 

 leaves of the vine, cocoons of a beautiful red have been obtained, and by 

 the employment of lettuce, others of a rich emerald green. By another 

 Frenchman, silk of a beautiful yellow, of a fine green, and of a violet 

 have been obtained by feeding the silk-worms on lettuce or on white 

 nettle. An essential condition to the success of the experiment is to feed 

 the worms on the mulberry leaves during their early ages, and to change 

 the food twenty days prior to the introduction of the chrysalis state. 



There can be no doubt that the silk-bearing glands of the caterpillars 

 undergo a certain degree of modification, consequent upon the intro- 

 duction of foreign material into the insect's economy, whereby they adapt 

 themselves to the absorption of the proper elements from the general 

 circulation, necessary to give to the silk its characteristic colors. It is 

 clear that the color of the silk depends upon the food of the larva. Such 

 being a true statement of the facts of the case, why will not a changed 

 condition of the same food, evolved in obedience to the action of chemical 

 or physical forces in the parenchymatous matter of the leaves, have a 

 similar tendency ? If the different capacities of different leaves to produce 

 diverse effects are due to the chemical activities at work therein, bearing 

 in mind that the same simple elements enter into the composition of all 

 leaves, why will not leaves undergoing chemical and physical changes 

 have different effects upon the tender beings that appropriate them as- 

 food, as well as the same food in a stable condition ? 



