It is stated that although scarcity of food is an important factor in determining the appearance of males, temperature also plays an important part in their production. Kurg having found a few males in midsummer in pools which were nearly dried up was induced to attempt their artificial production. So successful was he, that “he obtained the males of forty species, in all of which the males had previously been unknown.” He proved that
any unfavourable change in the water causes the production of males, which appear as it dries up, as its chemical constitution changes, when it acquires an unfavourable temperature, or, in general, when there is a decrease in prosperity.
From which observations and many others quoted from Düring, Professor Brooks concludes that “among animals and plants, as well as in mankind, a favourable environment causes an excess of female births, and an unfavourable environment an excess of male births.”[28] According to Rolph, also, the percentage of females increases with the increase of favourable conditions of temperature and food.
Among insects the males appear first, thus showing that less time is required to develop them from the larval state. Of this Mr. Darwin says: “Throughout the great class of insects the males almost always are the first to emerge from the pupal state, so that they generally abound for a time before any female can be seen.”[29]
Recent observations show that among the human species nutrition plays a significant part in determining sex. Statistics prove that in towns and in well-to-do families there is a preponderance of girls, while in the country, and among the poor, more boys are born; also, that immediately following epidemics, wars, and famines, there is an excess of male births. On examination, it was found that in Saxony “the ratio of boy-births rose and fell with the price of food, and that the variation was most marked in the country.”[30]
That the female represents a higher development than the male is proved throughout all the various departments of nature. Among plants, staminate flowers open before pistillate, and are much more abundant, and less differentiated from the leaves, showing that they are less developed, and that slighter effort, a less expenditure of force, is necessary to form the male than the female. A male flower represents an intermediate stage between a leaf and a perfect, or we might say, a female flower, and the germ which produces the male would, in a higher stage, produce the female.[31] In reference to the subject of the relative positions of the female and male flowers in the Sedges, Mr. Meehan observes:
In some cases the spike of the male flowers terminates the scape; in others the male flowers occupy the lower place; in others, again they have various places on the same spike. It will be generally noted that this is associated together with lines of nutrition,—those evidently favoured by comparative abundance sustaining the female flowers.
To this Mr. Meehan adds:
And this is indeed a natural consequence, for, as vitality exists so much longer in the female than the male flowers, which generally die when the pollen has matured, it is essential that they should have every advantage in this respect.[32]
The most perfect and vigorous specimens of coniferous trees are of the female kind. In its highest and most luxuriant stage the larch bears only female blossoms, but so soon as its vigour is lost male flowers appear, after which death soon ensues.