. Biology; the story of living things. THE EPIC OF EVOLUTION 489 The activation upon occasion of the mammary glands, as well as the formation of antitoxins, and the acquisition of immunity to cer- tain disea"ses, are further examples of physiological adaptation to bodily needs. Psychological Adaptations Patterns of instinctive behavior which adapt an untaught cater- pillar to spin a cocoon of a definite sort, or direct an insect to lay its eggs upon a particular food-plant specific for its offspring which it will never see, as well as the inner urge that causes birds, and certain other an
. Biology; the story of living things. THE EPIC OF EVOLUTION 489 The activation upon occasion of the mammary glands, as well as the formation of antitoxins, and the acquisition of immunity to cer- tain disea"ses, are further examples of physiological adaptation to bodily needs. Psychological Adaptations Patterns of instinctive behavior which adapt an untaught cater- pillar to spin a cocoon of a definite sort, or direct an insect to lay its eggs upon a particular food-plant specific for its offspring which it will never see, as well as the inner urge that causes birds, and certain other animals, to migrate periodically, may possibly be cited as ex- amples of psychological adaptation. At any rate, the exercise of the nervous system that enables actors to repeat their lines unconsciously in dozens of plays, and by which musicians are able upon repetition to perform complicated and extensive scores without conscious effort, comes close to being an adaptation of a psychological nature. Genetical Adaptations Adaptations frequently work for the benefit of the species rather than for the welfare of the individual. The clever dandelion grows close to the ground in a flat rosette. This habit enables it to escape from browsing animals to a consider- able degree and to with- stand trampling. Its yel- low blossom lies low and bides its time until all is ready and then, just at the critical time, the hol- low stem shoots up like a fire ladder into the air almost overnight, bearing a cluster of white-tufted aviating seeds that are all prepared for distribu- tion. They are so deli- cately poised, pincushion- fashion, in their elevated position that the slightest breeze is sufficient to waft them on their way. All the many reproductive modifications, both structural and func- tional, which are involved in the fertilization of animal eggs as well. ^ — "€_. The adaptable dandelion, providing for itself and for its Please note that these images are extracted fro
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