. Evolution and disease . FiG. 78.—The cornea of an Ox with a patch of pihferous skingrowing from it. (After Partridge.) junctiva of an ox. Some of these patches of skinhave been examined microscopically and found tocontain parts which are characteristic of skin in othersituations of the body such as pigment, sebaceous,and sweat-glands. The developmental details of theconjunctiva indicate most conclusively that it is amodified piece of skin, and though in the individual ATAVISM OR REVERSION. 143 it does not pass from skin to mucous membrane, never-theless, as in the case of the flower, it now
. Evolution and disease . FiG. 78.—The cornea of an Ox with a patch of pihferous skingrowing from it. (After Partridge.) junctiva of an ox. Some of these patches of skinhave been examined microscopically and found tocontain parts which are characteristic of skin in othersituations of the body such as pigment, sebaceous,and sweat-glands. The developmental details of theconjunctiva indicate most conclusively that it is amodified piece of skin, and though in the individual ATAVISM OR REVERSION. 143 it does not pass from skin to mucous membrane, never-theless, as in the case of the flower, it now and thenindicates its ancestry by reverting to its original type ofstructure. Spurious Atavism.—It is so important not to con-. FiG. 79.—A congenital fold of skin stretching from the thighto the heel of a girl. (After Wolff.) found spurious instances with examples of genuinereversion or atavism, that, even at the risk of beingtedious, it is necessary to consider briefly a few in-teresting cases likely to be misinterpreted on superficialexamination. In 1888 Dr. Julius Wolff, of Berlin, published a 144 EVOLUTION AND DISEASE. description of a remarkable anomaly in the leg of agirl. Among other defects she had a broad triangularfold of skin stretching from the thigh to the heel, asshown in fig. 79. The malformation was congenitaland is in all probability unique ; at any rate, it is veryrare, for such exhaustive writers on the subject ofmalformations in general as Forster, St. Hilaire, Alhfeld,and Albers furnish no parallel case. On superficial examination a zealous evolutionistmight be induced to argue that we have here anattempt to produce a wing, or regard it as a reversionto the parachute-like folds of skin s
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectabnormalitieshuman
