490 INSTINCT OF INSECTS. 



You will not doubt my allowing the appositeness of 

 this question, when I frankly tell you, that so strikingly 

 do many of the preceding facts seem at first view the ef- 

 fect of reason, that in my original sketch of the letter you 

 are now reading, I had arranged them as instances of 

 this faculty. But mature consideration has convinced 

 me (though I confess the subject has great difficulties) 

 that this view was fallacious ; and that though some cir- 

 cumstances connected with these facts may, as I shall 

 hereafter show, be referable to reason, the facts them- 

 selves can only be consistently explained by regarding 

 them as I have here done, as examples of variations of 

 particular instincts : and this on two accounts. 



In the first place, these variations, however singular, 

 are limited in their extent: all bees are, and have always 

 been, able to avail themselves of a certain number, but 

 not to increase that number. Bees cemented their combs 

 when becoming heavy, to the top of the hive, with mitys, 

 in the time of Aristotle and Pliny as they do now ; and 

 there is every reason to believe that then, as now, they 

 occasionally varied their procedures, by securing them 

 with wax or with propolis only, either added to the up- 

 per range of cells, or disposed in braces and ties to the 

 adjoining combs. But if in thus proceeding they were 

 guided by reason, why not under certain circumstances 

 adopt other modes of strengthening their combs? Why 

 not, when wax and propolis are scarce, employ mud, 

 which they might see the martin avail herself of so suc- 

 cessfully ? Or why should it not come into the head of 

 some hoary denizen of the hive, that a little of the mortar 

 with which his careful master plasters the crevices, be- 

 tween his habitation and its stand, might answer the end 



