AN UNUSUAL PHYTO-BEZOAR.

WILLIAM TRELEASE.

In January, 1897, Dr. Francis Eschauzier, of San Luis Potosi, Mexico, sent to me two specimens (Plate XL.), one a ball of surprising accuracy of surface, measuring a little over three and one-half inches in diameter and weighing seven and one-half ounces, and the other one-half of a similar ball, about four inches in diameter and weighing four ounces,— stating that sixteen such balls of about the size of the specimens sent had been taken from the stomach of a bull at the Hacienda de Cruzes, and adding that he believed them to be composed entirely of an agglomeration of the fibers of some cacti, an undigested portion of which formed the nucleus. Subsequent inquiry resulted in the additional information that the chief food of cattle at that season of the year consisted of five Opuntias, and that the animal from which the specimens were obtained was wild, of fighting stock, and consequently allowed to seek food where it could be found, instead of being fed upon cacti which had been roasted, as is the custom with other stock. My informant further stated that the wild bulls drink very little water while feeding upon cacti, and that the animal in question, which was ten years old, had not exhibited any signs of illness, though for some time the large size of its abdomen had attracted the attention of the vaqueros, but, owing to the intractability of the animal, no examination of it could be made until after its death.

The specimens, which were exhibited to the Academy Feb. 15, 1897, are of a brown color, and in appearance somewhat suggest felt or rubbed sole leather, and on examination prove to be composed, aside from the small nucleus at the center, of the barbed hairs with which the pulvini of the Platopuntias are armed. To the barbs with which these hairs are covered is due their power of felting together, and there

is every indication that, starting about some small nucleus of vegetable fiber, they have been compacted into the dense, felty texture by the visceral movements of the animal, to which, causing friction against one another, their perfectly round form is attributable.

It is well known that the Opuntias produce spines and two kinds of trichomes. In some of the Cylindropuntias, each spine is invested by a deciduous sheath, which is downwardly barbed, so that a person or animal brushing carelessly against a plant is certain to remove some of the barbed sheaths. In the Platopuntias, to which the ordinary flat-stemmed prickly pears, and the species upon which the Mexican cattle are fed, belong, the spines, when present, are destitute of such a sheath, and protect the plant simply because of their rigidity and pungency. The spines originate in what have been called pulvini, which in this genus of cacti are coated with delicate, flexible hairs, divided by partitions into a number of cells, and stiff, thick-walled hairs, several millimeters in length and from one to two tenths of a millimeter in diameter at the base. These are very lightly attached to the epidermis of the plant, so that when the pulvinus is touched they are certain to be removed in considerable numbers, the fine points of the stiffer ones penetrating the skin, and the barbs with which they are closely beset preventing their ready withdrawal.

Balls formed largely of the hair of animals are often found in the stomachs of ruminants, to which they have found their way when the animals have licked themselves, and not infrequently smaller balls, with a hard, glossy surface, are found in the stomachs of cattle, horses and, as Dr. Eschauzier informs me, of goats. In general, such a formation is spoken of as a bezoar, and all of the principal agricultural museums contain good specimens of them. One of the largest of the ordinary hair balls which has come to my notice is preserved in the museum of the Iowa Agricultural College, and is stated to weigh four pounds and eleven ounces and to measure twentyfive and one-half inches in circumference. The smaller, harder structures, which seem to be primarily of biliary composition about some sort of nucleus, rarely measure more