NATURAL SCIENCES OF PHILADELPHIA. 325 



and in the course of two or three days found it hollowed out to a mere shell ; 

 that too, in a short time, would be cut to pieces and carried off. Not a green 

 thing is suffered to grow on the pavement, with the exception of a single spe- 

 cies of grain-bearing grass, (Aristida stricta.) This the ant nurses and culti- 

 vates with great care ; having it in a circle around and two or three feet from the 

 center of the mound. It also clears away the weeds and other grasses all 

 around outside of the circular row of Aristida, to the distance of one or two 

 feet. The cultivated grass flourishes luxuriantly, producing a heavy crop of 

 small, white, flinty grains, which, under the microscope, have the appearance 

 of the rice of commerce. When it is ripe it is harvested by the workers, and 

 carried, chaff and all, into the granary cells, where it is divested of the chaff, 

 which is immediately taken out and thrown beyond the limits of the pave- 

 ment alwaj s to the lee side. The clean grain is carefully stored away in dry 

 cells. These cells are so constructed that water cannot reach them, except in 

 long wet spells, when the earth becomes thoroughly saturated, and dissolves the 

 cement with which the granary cells are made tight. This is a great calami- 

 ty, and if rain continues a few days it will drown out the entire com- 

 munity. In cases, however, where it has continued long enough only to 

 wet and swell their grain, as soon as a sunny day occurs they take it all out, 

 and spreading it in a clean place, after it has sunned a day or two, or is fully 

 dry, they take it in again, except the grains that are sprouted ; these they in- 

 variably leave out. I have seen at least a quart of sprouted seeds left out at 

 one place. 



They also collect the grain from several other species of grass, as well as 

 seed from many kinds of herbaceous plants. They like almost any kind of 

 seeds red pepper seeds seem to be a favorite with them. 



In a barren rocky place in a wheat field, a few days after harvest, I saw quite 

 a number of wheat grains scattered over the pavement of an ant city, and the 

 laborers were still bringing it out. I found the wheat quite sound, but a little 

 swelled. In the evening of the same day I passed there again ; the wheat had 

 dried, and they were busily engaged carrying it in again. 



The species of grass they so carefully cultivate is a biennial. They sow it 

 in time for the autumnal rains to bring it up. Accordingly, about the first of 

 November, if the fall has been seasonable, a beautiful green row of the ant rice, 

 about 4 inches wide, is seen springing up on the pavement, in a circle of 14 to 

 15 feet in circumference. In the vicinity of this circular row of grass they 

 do not permit a single spire of any other grass or weed to remain a day; leav- 

 ing the Aristida untouched until it is ripe, which occurs in June of the next 

 year they gather the seeds and carry them into the granaries as before stated. 

 There can be no doubt of the fact that this peculiar species of grass is in- 

 tentionally planted, and, in farmer-like manner, carefully divested of all other 

 grasses and weeds during the time of its growth, and that after it has matured, 

 and the grain stored away, they cut away the dry stubble and remove it from 

 the pavement, leaving it unencumbered until the ensuing autumn, when the 

 same species of grass, and in the same circle, appears again, receiving the 

 same agricultural care as did the previous crop ; and so on, year after year, as 

 I know to be the case on farms where there habitations are, during the sum- 

 mer season, protected from the depredations of cattle. Outside of the fields 

 they sow the grass seeds, but the cows crop it down two or three times, when, 

 finding that there is no chance to carry on their agricultural pursuits, they cut 

 it all away and re-establish the clean pavement. Our cattle did not often crop 

 the ant rice until their increased numbers have forced them to feed on all 

 kinds of grass. That, however, has turned out favorably to the ant interest. 

 For, while the prairies are being denuded of the stronger grasses, we have a 

 delicate little biennial barley (Hordium pusillum) that is filling all the naked 

 places. It rises from 3 to 6 inohes, producing fine grain for ant consumption. 

 It matures about the last days of April, and from that time all the agricultural 

 ants are seen packing it home daily through the summer. This species of ant 



1866.] 



