ArrEXDix. :-57;h 



all sorts of sounds, and yet that in a state of nature they 

 never display these powers.* 



As there is often much difficulty in imagining how an 

 instinct could first have arisen, it may be worth while to give 

 a few, out of many cases, of occasional and curious habits, 

 which cannot be considered as regular instincts, but which 

 might, according to our views, give rise to such. Thus, 

 several cases are on recordf of insects which naturally have 

 very different habits having been hatched witliin tlie bodies 

 of men — a most remarkable fact considering the temperature 

 to which tliey have been exposed, and which may explain 

 the origin of the instinct of the Gad-fly or Oestrus. We can 

 see how the closest association might be developed in 

 Swallows, for Lamarck:|: saw a dozen of these birds aiding a 

 pair, whose nest had been taken, so effectually that it was 

 completed on the second day ; and from the facts given by 

 Macgillivray§ it is impossible to doubt that the ancient 

 accounts are true of the Martins sometimes associating and 

 entombing alive sparrows which have taken possession of one 

 of their nests. It is well known that the Hive-bees which 

 have been neglected " get a habit of pillaging from their more 

 industrious neighbours," and are then called corsairs ; and 

 Huber gives a far more remarkable case of some Hive-bees 

 which took almost entire possession of the nest of a Humble- 

 bee, and for three weeks the latter went on collecting honey 

 and then regorged it at the solicitation, without any violence, 

 of the Humble-bee. 1 1 We are thus reminded of those Gulls 

 (Lestris) which exclusively live by pursuing other gulls and 

 compelling them to disgorge their food.lf 



In the Hive-bee actions are occasionally performed which 



* Blackwall's Researches in Zoology^ 1834, p. 158. Curier long ago 

 remai'ked that all the passeres have apparently a similar structure in their 

 vocal organs; and yet only a few, and these the males, sing; sLo\nng that 

 fitting structure does not always give rise to corresi^onding habits. [Concern- 

 ing birds which imitate sounds when in captivity not doing so in a state of 

 nature, see p. 222, where there is evidence of certain wild birds imitating the 

 sounds of other species. — G-. J. R.] 



t Rev. L. Jenyns, Observations in Nat. Hist., 1846, p. 280. 



X Quoted by Ueoifry St. Hilaire in Anns, des Mtis., tome ix, p. 471. 



§ British Birds, vol. iii, p. 591. 



II Kirby and Spence, Entomology, vol. ii, p. 207. The case given by 

 Huber is at p. 119. 



^ There is reason to suspect (Macgillivray, British Birds, vol. v, p. 500) 

 that some of the species can only digest Ibod which has been partially 

 digested by other bii'ds. 



