Sheep’s sorrel and common sorrel, both commonly known as “sooricks,” were more harmful half a century ago than they are at present. Cultivation and the rotation of crops have reduced their quantity, but their enormous power of spreading can be witnessed in a poor, thin, or peaty soil, where the crops, especially grass, are meagre. There they spread, and sometimes with such vigour that they push every other plant aside. Both kinds of sorrel are common. The one with arrow-shaped leaves is called common sorrel; that with spear-shaped leaves, sheep’s sorrel. Their leaves, which have a very acid taste, often turn reddish. Another common and pretty little flower is prunella or self-heal. Whorls of green bracts and violet flowers form a dense, short spike. It grows from four to six inches high, and is to be met with on dry soils, and although fairly common in oats, flourishes best in second year’s grass. It is one of the large order of _Labiates_, a group which includes the dead-nettle and the hemp-nettle, and when abundant it is a clear indication of the exhaustion of some ingredients of the soil—often lime. When fields are brought to a high state of cultivation, or are near enough the seashore to get an abundant supply of sand, it almost disappears; but when they are impoverished, it soon returns. These are only a few of the weeds which every farmer knows well. They are worth study, for it is only when we know how they grow and spread that we are able to prevent their increase. The cultivation and manuring of the soil and the sowing of seeds are only one side of the farmer’s work; he has to remove the wild growth as well as to promote the growth of what he sows. Otherwise his fields will bear two crops at a time, one of nature’s sowing and one of his own, and of these two the natural crop is likely to be the more flourishing. [Illustration] HOME LIFE ON THE ROCKS. Guillemots.