34 THE ZOOLOGIST. 



who had collected them while engaged in the U.S.A. Geological Survey in 

 the above-mentioned districts, 1880-81. 



An essay " On Instinct," by the late Mr. Charles Darwin, was then 

 read by the Zoological Secretary. 



After detailing sundry facts with reference to the migratory instincts of 

 different animals, the autlior of the essay suggests a theory to account for 

 them. This theory is precisely the same as that which was subsequently 

 and independently enunciated by Mr. Wallace in 'Nature,' vol. x. p. 459 

 (1874). Thus, to quote from the essay : — " During the long course of ages, 

 let valleys become converted into estuaries and then into wider arms of the 

 sea; and still I can well believe that the impulse (originally due to seeking 

 food) which leads the pinioned goose to scramble northwards, would lead 

 our l)ird over the trackless waters ; and that, by the aid of the unknown 

 power by which many animals (and savage men) can retain a true course, 

 it would safely cross the sea now covering the submerged path of its ancient 

 journey." The next topic considered is that of instinctive fear. Many facts 

 are given, showing the gradual acquisition of such instinctive fear, or here- 

 ditary dread of man, during the period of human observation. These facts led 

 Mr. Darwin to consider the instinct of feigning death, as shown by sundry 

 species of animals when in the presence of danger. Seeing that " death is an 

 unknown state to each living creature," this seemed to him "a remarkable 

 instinct," and accordingly he tried a number of experiments upon the 

 subject with insects, which proved that in no one case did the attitude in 

 which the animal " feigned death " resemble that in which the animal really 

 died ; so that the instinct really amounts to nothing else, in the case of 

 insects at all events, than an instinct to remain motionless, and therefore 

 inconspicuous, in the presence of danger. From the facts given with 

 regard to certain vertebrated animals, however, it is doubtful how far this 

 explanation can be applied to them. A large part of the essay is devoted to 

 " Nidification and Habitation," with the object of showing, by an accumu- 

 lation of facts, that the complex instincts of nest building in birds, and of 

 constructing various kinds of habitations by mammals, all probably arose 

 by gradual stages under the directing influence of natural selection. Among 

 other "miscellaneous remarks" on instincts in general he notes, first, the 

 variability of instinct is proved by sundry examples ; next, the fact of double 

 instincts occurring in the same species ; after which, " as there is often 

 much difficulty in imagining how an instinct could first have arisen," it is 

 thought " 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." Finally, cases of special 

 difficulty are dealt with ; these may be classified under the following 

 heads: — (1) similar instincts in uuallied animals; dissimilar instincts in 

 allied animals ; (3) instincts apparently detrimental to the species which 



