INSTINCT OF INSECTS. 589 



Of those that fly abroad, what conception can we form of the cause which, 

 while one set is gathering honey or pollen, leads another company to load 

 their legs with pellets of propolis ? Are we to say that the instinct of the 

 former is excited by one sensation, that of the latter by another ? But 

 why should one sensation predominate in one set of bees, while another 

 takes the lead in a second ? — or how is it that these different instincts are 

 called up precisely in the degree which the actual and changing state of 

 things in the hive requires ? Of those which remain at home, what is it 

 that determines in one party the instinct of building cells to prevail ; in 

 another that of ventilating the hive ; in a third that of feeding the young 

 brood ? For my own part, I confess that the more I reflect on this sub- 

 ject, and contrast the diversity of the means with the regularity and 

 uniformity of the end, the more I am lost in astonishment. The effects 

 of instinct seem even more wonderful than those of reason, in the same 

 manner as the consentaneous movements of a mighty and divided army, 

 which, though under the command of twenty generals, and from the most 

 distant quarters, should meet at the assigned spot at the very hour fixed 

 upon, would be more surprising than the steam-moved operations, however 

 complex, of one of Boulton's mints. 



For the sake of distinctness and compression, I have confined myself 

 in considering the numbers of the instincts of individual insects to a single 

 species, the bee ; but if the history of other societies of these animals — 

 wasps, ants, &c. detailed in my former letters, — be duly weighed, it will 

 be seen that they furnish examples of the variety in question fully as 

 striking. These corroborating proofs I shall leave to your own inference, 

 and proceed to the third head, under which I proposed to consider the 

 instincts of insects — that of their extraordinary development. 



The development of some of the instincts of the larger animals, such as 

 those of sex, is well known to depend upon their age and the peculiar 

 state of the bodily organs ; and to this, as before observed, the succession 

 of different instincts in the same insect, in its larva and perfect state, is 

 closely analogous. But what I have now in view is that extraordinary 

 development ormstmct'A'hich is dependent not upon the age or any change 

 in the organization of the animal, but upon external events — which in 

 individuals of the same species, age, and structure, in some circumstances 

 slumbers unmoved, but may in others be excited to the most singular and 

 unlooked-for action. In illustrating this property of instinct, which, as far 

 as I am aware, is not known to occur in any of the larger animals, I shall 

 confine myself as before to the hive-bee ; the only insect, indeed, in which 

 its existence has been satisfactorily ascertained, though it is highly probable 

 that other species living in societies may exhibit the same phenomenon. 



Several of the facts occurring in the history of bees might be referred 

 to this head ; but I shall here advert only to the treatment of the drones 

 by the workers under different circumstances, and to the operations of the 

 latter consequent upon the irretrievable loss of the queen — facts which 

 have been before stated to you, but to the principal features of which my 

 present argument makes it necessary that I should again direct your 

 attention. 



If a hive of bees be this year in possession of a queen duly fertilized^ 



50 



