398 PERFECT SOCIETIES OF INSECTS. 



and pupa, since nature does nothing in vain, may probably assist this 

 action, and render the parts of the animal more capable of such exten- 

 sion than if it continued in a horizontal position. 



We know, with respect to the human species and the larger animals, 

 that numerous differences, both as to the form and relative proportion of 

 parts, occur continually. The cause of these differences we cannot always 

 ascertain ; yet in many instances they may either be derived from the 

 nutriment which the embryo receives in the womb, or from the greater or 

 less dimensions or higher or lower temperature of that organ — a case that 

 analogically would not be very wide of that of the grub or embryo of a 

 bee enclosed in a cell. Some of the differences in man I now allude to 

 may often be caused by a particular diet in childhood ; a warmer or a 

 colder, a looser or a tighter dress, or the like. Thus, for instance, the 

 Egyptians, who went bare-headed, had their skulls remarkably thick ; 

 while the Persians, who covered the head with a turban or mitre, were 

 distinguished by the tenuity of theirs. Again, the inhabitants of certain 

 districts are often remarkable for peculiarities of form, which are evidently 

 produced by local circumstances. 



The following reasoning may not be inapplicable to the development 

 or non-development, according to their food and habitation, of the ovaries 

 of these insects. An infant tightly swathed, as was formerly the custom, 

 in swaddling bands, without being allowed the free play of its little limbs, 

 fed with unwholesome food, or uncherished by genial warmth, may from 

 these circumstances have so imperfect a development of its organs as to 

 be in consequence devoted to sterility. When a cow brings forth two 

 calves, and one of them is a female, it is always barren, and partakes in 

 part of the characters of the other sex.^ In this instance, the space and 

 food that in ordinary cases are appropriated to one are divided between 

 two ; so that a more contracted dwelling and a smaller share of nutriment 

 seem to prevent the development of the ovaries. 



The following observations, mostly taken from an essay of the cele- 

 brated anatomist John Hunter, in the Philosophical Transactions, since 

 they are intimately connected with the subject that we are now consider- 

 ing, will not be here misplaced. In animals just born, or very young, 

 there are no peculiarities of shape, exclusive of the primary distinctions, 

 by which one sex may be known from the other. Thus secondary dis- 

 tinctive characters, such as the beard in men, and the breasts in women, 

 are produced at a certain period of life ; and these secondary characters, 

 in some instances, are changed for those of the other sex ; which does 

 not arise from any action at the first formation, but takes place when the 

 great command, " Increase and multiply," ceases to operate. Thus 

 women in advanced life are sometimes distinguished by beards ; and after 

 they have done laying, hen-birds occasionally assume the plumage of the 

 cock : this has been observed more than once by ornithologists, more 

 particularly with respect to the pheasant and the pea-hen.^ For females 

 to assume the secondary characters of males, seems certainly a more 



» See J. Hunter's Treatise on certain parts of the Animal (Economy.* 

 2 Pfiilos. Trans. 1792, viii. 167, Hunter On certain Parts of the Animal (Economy, p. 65. 

 Latham, Synops. ii. 672. t. 60. 



