Fig. 33 _a_ is a drawing of a fruit of false burnet. The section _b_ shows it to be quadrangular, with a wing at each angle, and to possess two seeds in each capsule. The capsules are rather muricated (_i.e._ furnished with short excrescences, and not regularly wrinkled, like the sainfoin). Now the burnet is easily separable from a sample of sainfoin, as the former readily passes through the sieve; but the objection to sift it may be well understood when the bulk is diminished by the amount of the burnet, and also that of the smaller sainfoin seeds, which pass through at the same time. The best plan, then, to pursue is to mill the sainfoin seed, in which case its outer covering is removed, and you simply have a sample of kidney-shaped pure seed-like enlarged clover-seeds, in which the burnet may be detected, because it will not mill, but simply gets its wings broken off, so that the wrinkled two-seeded capsule still remains. Now the fact of the burnet being a two-seeded capsule is most important to be noticed, as, from analyses we have made of dirty sainfoin crops, we have estimated as follows:— +-------------------------------+----------+--------+----------+ | Crops. | Sainfoin | Burnet | Other | | | Plant. | Plant. | Weeds. | +-------------------------------+----------+--------+----------+ |Crop in Berkshire, 3rd year | 10 | 50 | 40 = 100 | |Crop in Cirencester, 3rd year | 5 | 25 | 70 = 100 | +-------------------------------+----------+--------+----------+ Here, then, we have a large proportion of burnet, surely much more than could be accounted for from the number of capsules, at least we will hope so; but when we consider that the capsule of the sainfoin is _single-seeded_ and that of the burnet is _two-seeded_, we may readily conceive how each capsule of the latter may at least grow a single seed, but the best sample of the former could hardly be expected to all come up. Now, as we have as many as 64,000 capsules of burnet in a bushel of sainfoin seed, that × 2 = 128,000 seeds, and when we consider that the burnet grows so much faster than the sainfoin, we have two elements for the success of the former, namely, the certainty of getting its crop, and the equal certainty of smothering out a large proportional of what may germinate of the seeds of the sainfoin. This matter would not be of such importance if the burnet was equal in point of feeding properties, but it is not so, for whatever quality be in the smaller and more succulent _P. sanguisorba_ form, the _P. muricatum_ is, on the contrary, hard and woody, and almost useless. CHAPTER XXI. ON CLOVER SICKNESS.