326 PHYSIOLOGY. 



pations. But females are not always so agreeable ; many violently 

 resist and maintain their independence in a severe contest, in which in 

 general the males are subdued. The Asili, which alight upon leaves 

 and the glowing sand to sun themselves, are frequently disturbed from 

 this tranquillity by the arduous male, but they do not generally yield, 

 for they defend their innocence as valiantly as successfully. The 

 LibellulfB also do not copulate flying, but sitting ( 152) ; the male, in 

 these, attacks the reposing female, who yields not until the sexual 

 instinct is fully developed, previously to which she takes wing and 

 escapes ; but their union in flight, on the contrary, although indeed 

 an expression of love, and reciprocal, is certainly no copulation. 



Other insects, which are more truly crepuscular and nocturnal, 

 copulate merely at those times. The Bombyces sit immoveably 

 during the whole day, and during even the brightest sunshine they 

 do not yield to the developed sexual impulse. The males, however, 

 are more impetuous ; they swarm about the female even at improper 

 times ; for example, Liparis dispar, at noon, and when the sun is 

 hottest, but yet without finding her propitious to their suit. But so 

 soon as evening approaches, the female also arouses from her slumber, 

 and twilight, which increases the susceptibility of all sensible beings, 

 acts likewise inlluentially upon the Noctuce and crepuscular moths. 

 They are now urgent in their endeavours to approach the female, who 

 does not, however, play the prude, but is regardful of the favourite, 

 and yields to his solicitation. But, at this period, they are entirely 

 absorbed in each other; all activity and motion cease during copulation. 

 They sit apparently lifeless beside each other, with withdrawn antennae, 

 and limbs solely occupied with the business in hand, which, at least 

 for the male, is the last he will pursue: they, therefore, enjoy it as long 

 as possible ; indeed, the latter frequently falls down lifeless when the 

 female frees herself from him. This phenomenon can be observed daily, 

 during the summer, in the common Liparis dispar, Salicis, and in others 

 of the Bombyces. Towards evening their connexion commences, and 

 it is still continued on the following morning, but it is not rarely that 

 the male is already dead, or, at least, so exhausted, that it may be more 

 classed with the dead than with the living. 



The Coleoptera also appear to copulate more towards evening. This 

 is well known in the cockchafer, which only about dusk acquires its 

 full vivacity. The same is the case with the dung beetle and stag 

 beetle. We, indeed, frequently rind them thus occupied during the 



