12 NATURAL SCIENCE. July, 



has recently called attention to a new source of trouble in the hairs of 

 the calyx of the crimson clover, Trifolium incarnatiim. Up to the 

 time of flowering these hairs are soft and flexible, but they afterwards 

 become stiff" and almost needle-like in character. If hay made from 

 over-ripe clover is fed to cattle, these hairs, which are barbed, form 

 balls of a tough, felt-like consistency three or four inches in diameter, 

 which ultimately cause death through peritonitis or some related 

 ailment. The first deaths from this cause in the United States were 

 noted in 1895, and farmers are cautioned against allowing this clover 

 to become too ripe before making it into hay. 



The tops of the spineless cactus, Anhalonium Leu/ini, of Southern 

 Texas, which contain an active poison, serve as articles of trade 

 among the Indians, who use them as an intoxicant or stimulant 

 during their dances or religious ceremonies. Mr. Coville considers 

 that, in the absence of spines, this bitter, poisonous property serves 

 as a protection against animal enemies. 



The Horse's Hoof. 



The hoof of quadruped mammals is so unique in its way that 

 any contribution towards a knowledge of its histology and develop- 

 ment is always welcome. Professor Mettam, in his presidential 

 address to the Scottish Microscopical Society, published in extenso in 

 the Vetevinarian of the current year, gives an account of his original 

 observations on the subject, and lays special stress on the mode of 

 development of those horny lamellae which are to be seen running in 

 a vertical direction on the inner surface of the wall of the hoof of the 

 horse. The surface of contact of the corium or dermis with the 

 epidermis is, in the early stages of -development, smooth and devoid of 

 ridges. This has always been assumed in the past, but it has been 

 left for Professor Mettam to demonstrate the fact, and to fix the age 

 at which it is most clearly seen, viz., at seventy or eighty days in the 

 case of the equine foetus. When the corrugations first appear in the 

 surface of contact, they arise by the dipping of the rete Malpighii of 

 the epidermis into the corium, and not by outgrowths of the corium 

 into the epidermis, as has hitherto been held. The horny laminge are 

 the cornified cores of these epidermal ingrowths, and remain standing 

 out from the inner surface of the wall of the hoof after the removal, 

 by maceration or other artificial means, of the uncornified inner layers 

 of the epidermis. The laminae are simple at first, but secondary 

 ridges soon develop upon the lateral surfaces. Professor Mettam also 

 gives an account of the Pacinian and other corpuscles found in the 

 sensitive frog of the foot, and the comparison which he draws 

 between the histological structure of the sweat glands of the horse's 

 frog and that of the interdigital glands of the sheep and the ceruminous 

 glands of the external ear is interesting. 



