From the facts elaborated by our guides in this matter, it would seem that the female is the primary unit of creation, and that the male functions are simply supplemental or complementary. Parthenogenesis among many of the lower forms of life would seem to favour this view. We are given to understand that under conditions favouring katabolism, the males among Rotifera wear themselves out, under which conditions the females become katabolic enough to do without them. Among the common Rotifera, the males are almost always very different from the females, and much smaller. Sometimes they seem to have dwindled out of existence altogether, for only the females are known. In other cases, though present, they entirely fail to accomplish their proper function of fertilization, and, as parthenogenesis obtains, are not only minute, but useless.[24] [24] _The Evolution of Sex_, 1890, p. 20. So long as food is plentiful, the females continue to raise parthenogenetic offspring, but with the advent of hard times, when food is scarce or of a poor quality, the parthenogenetic series is interrupted by the appearance of males. Although, unaided by the male, the female of certain species is able to reproduce, he has never been able to propagate without her co-operation. Concerning the conditions which underlie the production of females and males we have the following from _The Evolution of Sex_, by Geddes and Thomson: Such conditions as deficient or abnormal food, high temperature, deficient light, moisture, and the like, are obviously such as would tend to induce a preponderance of waste over repair—a katabolic habit of body,—and these conditions tend to result in the production of males. Similarly, the opposed set of factors, such as abundant and rich nutrition, abundant light and moisture, favour constructive processes, _i.e._, make for an anabolic habit, and these conditions result in the production of females.[25] [25] _The Evolution of Sex_, p. 50. Among the lower orders of animal life, notably insects, we are assured that an excess of females denotes an excess of formative force, and that an excess of males indicates a deficiency on the part of the parents. In the case of bees, the queen, which is the highest development, is produced only under the best circumstances of nutrition, while the birth of the drone, which is the lowest result of propagation, is preceded by extremely low conditions.