. Evolution and disease . Fig. 13.—The head of a Polish fowl to show the feathery tuft.(After Darwin.) A somewhat similar condition is seen in ducks. Pre-served in the museum of the Royal College of Surgeonsis a duckling with a small tumour projecting from thetop of its head ; hanging from the side of the tumour isa miniature but well-developed foot (fig. 14). Theswelling is connected with the ducklings brain by meansof a small rounded hole in the summit of the cranium. Animals and Plants under Domestication. ENLARGEMENT OF PARTS FROM USE. 25 Isidore Geoffroy Saint-Hilaire ^ describes and figu
. Evolution and disease . Fig. 13.—The head of a Polish fowl to show the feathery tuft.(After Darwin.) A somewhat similar condition is seen in ducks. Pre-served in the museum of the Royal College of Surgeonsis a duckling with a small tumour projecting from thetop of its head ; hanging from the side of the tumour isa miniature but well-developed foot (fig. 14). Theswelling is connected with the ducklings brain by meansof a small rounded hole in the summit of the cranium. Animals and Plants under Domestication. ENLARGEMENT OF PARTS FROM USE. 25 Isidore Geoffroy Saint-Hilaire ^ describes and figuresthe head of a duck with a tuft of feathers on the occiputand a foot. In describing the foot Saint-Hilaire statesthat the cranium underlying the tuft was defective, andespecially notes that the cranial opening was similar tothat found in les poules a tete huppee. V. w ^ Fig. 14.—Head of a duckling willi ;i iiiiiiotir and abnormal footgrowing from tlic occiput. During life this foot, like the normal pair, was of abeautiful orange-yellow colour. Some who saw the duckwere suspicious that the foot had been engrafted on to theocciput accidentally : such an opinion had no foundation. • Des Anomalies de Iorganisation chez Ihomme ct les Ani-maux, tome iii. p. 194. 26 E VOLUTION AND DISEASE. Tiedemann I in 1831 described and figured the skullof a duck with a foot growing from its occiput. Thereis a fancy breed of ducks in which the distinguishingfeature is the presence on the occiput of a rounded knobor swelling covered with feathers. The acquisition and transmission of such charactersshed light on some rather puzzling conditions. Ab-normal growth of hair induced by contact with irritatingsubstances may explain the presence of hair in such acurious situation as the stomach of a crayfish and thehairs which form the remarkable plug around the pyloricori
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectabnormalitieshuman
