In regard to several of the lower animals, we find, in a number of cases where there are accurate data, that the individual goes on year after year producing young. Whether they ever grow old, in the sense of losing their power of reproduction, has not been definitely determined, but there is, so far as I know, no evidence to show that such a process takes place, and these animals appear to have the power of reproducing themselves indefinitely. The phenomenon of old age (apart from its possible connection with the cessation of the power of reproduction), which leads to the death of the individual, has been looked upon by a few writers as an adaptation of the individual for the good of the species. It has been pointed out by these writers that the longer an individual lives, the more likely it is to become damaged, and if along with this its powers of reproduction diminish, as compared with younger individuals, then it stands in the way and takes food that might be used by other, younger individuals, that are better able to carry on the propagation of the race. It is assumed, therefore, that the life of the individual has been shortened for the benefit of the race. Whether such a thing is probable is a question that will also be discussed later. We are chiefly concerned here only in recording the different groups of phenomena that have been regarded by biologists as adaptations. The so-called secondary sexual characters such as the brighter colors of the males, ornaments of different kinds, crests, color-pattern, tail feathers, etc., organs of offence and of defence used in fighting members of the same species, present a rather unique group of adaptations. These characters are supposed to be of use to the individual in conquering its rivals, or in attracting the females. They may be considered as useful to the individual in allowing it to propagate at the expense of its rivals, but whether the race is thereby benefited is a question that will be carefully considered later. The colors of flowers, that is supposed to attract insects, have been already mentioned. The sweet fluid, or nectar, secreted by many flowers is sought by insects, which on entering the flowers bring about cross-fertilization. Thus while the nectar seems to be of no immediate service to the plant itself, it is useful to the species in bringing about the fertilization of the flowers. The odors of flowers also serve to attract insects, and their presence is one of the means by which insects find the flowers. This also is of advantage to the race. Organs of Little Use to the Individual