. Nature sketches in temperate America, a series of sketches and a popular account of insects, birds, and plants, treated from some aspects of their evolution and ecological relations . n the battleamong themselves, the successful combatant winning the femaleand thereby transmitting these characters to the offspring. It is not always possible, in the nature of the case, to deter-mine how far sexual selection of this sort plays a part in theperfecting of these peculiar structures of the male, for afterall it may be that natural selection has had something to doalso in perfecting them. On this v
. Nature sketches in temperate America, a series of sketches and a popular account of insects, birds, and plants, treated from some aspects of their evolution and ecological relations . n the battleamong themselves, the successful combatant winning the femaleand thereby transmitting these characters to the offspring. It is not always possible, in the nature of the case, to deter-mine how far sexual selection of this sort plays a part in theperfecting of these peculiar structures of the male, for afterall it may be that natural selection has had something to doalso in perfecting them. On this very point there was a differ-ence of opinion between Darwin and his contemporary, latter did not make the fine distinction of supposing sexualselection to be a contributing factor in these cases, but reliedon natural selection as being sufficient for their production. Even in insects we find the so-called secondary sexual char-acters, but they are present only in the male. A most remark-able example of this type of structure in insects occurs in thestriped meadow cricket, described at some length further has an alluring gland on the back between the wings which. A Pair of the Slender Cone-head Grasshoppers{Conocephalus attenuatus [ensiger]) On golden, rod; the female is shoxcn beloK-. The topjigure is the male of the very small stiiped mcadoic grasshopper [Xiphidium fasciatum) . From a photograph EVOLUTION AND NATURAL SELECTION 23 secretes a plasmatic fluid quite inviting to the female. Thispale green insect, in the male sex, has his forewings also somodified that when he shuflBes them together over his body theyproduce a high-pitched shrilhng, which attracts the female,if within hearing distance. Then he brings into action boththe wings and the organ above referred to. The shrilhngsound, together with the secretion in the hollow glands on hisback, entices her to cKmb on him, and there she partakes ofhis loving cup. This performance is preliminary to the nupti
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbirds, booksubjectins
