horn
A hard substance growing on the heads of certain animals, and particularly on cloven-footed quadrupeds; usually projecting to some length and terminating in a point. Horns are generally bent or curving, and those of some animals are spiral. They serve for weapons of offense and defense. The substance of horns is gelatinous, and in Papin’s digester it may be converted into jelly. Horn is an animal substance, chiefly membranous, consisting of coagulated albumen, with a little gelatin and phosphate of lime. The horns of deer possess exactly the properties of bone, and are composed of the same constituents, only the proportion of cartilage is greater.