. Evolution and disease . 24 EVOLUTION AND DISEASE. same way that the hairy tuft may be accounted for inthe back of those with spina bifida occulta. Thesefowls arc extremely uncertain in their gait, given toperforming circular movements, and walking sideways ifexcited, as though they possessed an unstable nervoussystem. Darwin was assured that we had here to dealwith a character first acquired and transmitted by th^hen. I. 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
. Evolution and disease . 24 EVOLUTION AND DISEASE. same way that the hairy tuft may be accounted for inthe back of those with spina bifida occulta. Thesefowls arc extremely uncertain in their gait, given toperforming circular movements, and walking sideways ifexcited, as though they possessed an unstable nervoussystem. Darwin was assured that we had here to dealwith a character first acquired and transmitted by th^hen. I. 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
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectabnormalitieshuman
