“It is when we consider the round or roundish type of alfalfa seed that there is difficulty in distinguishing from alfalfa the seeds of Yellow trefoil and of Sweet clover (illus. opp. p. 26), which latter frequently occurs as a weed seed, and possibly in some cases in sufficient quantity to be suspected as an adulterant. By comparison of the seeds of alfalfa with the two adulterants just mentioned, (p. 26) the resemblances and differences of the three species will become evident. In general the seeds of Yellow trefoil are shorter and rounder than those of alfalfa, the largest seeds of trefoil measuring 0.0629 inch wide by 0.0897 inch long; whereas the largest alfalfa seeds measure 0.0653 inch wide by 0.1153 inch long; so that the largest alfalfa seeds are a trifle wider and more than a third again as long as the largest trefoil seeds. The smallest seeds of Yellow trefoil are usually plumper and shorter than those of alfalfa (0.0511 inch wide by 0.0291 inch long, as compared with 0.0496 inch wide by 0.0751 inch long in alfalfa); nevertheless, among both the small and the large seeds, so far as the criterion of size goes, individuals occur that equally well belong to either species, and the average differences in size are not so great as the differences found on comparing the largest and the smallest seeds of the two species, the average for the trefoil being 0.0574 inch by 0.0799 inch, and for alfalfa 0.0582 inch by 0.0944 inch. So it will be seen at once that while trefoil seeds as a rule are smaller, shorter and rounder than those of alfalfa, the rule is transgressed by many individuals. We must, therefore, turn to the form and general outline of the seed. A farmer can detect at once an attempt to substitute wholly Yellow trefoil for alfalfa seed by the fact that _in no case will the kidney-shaped or the regular-pointed types of seed be found in trefoil, whereas these always occur in alfalfa_. (Illustrated opp p. 26.) “In the more common cases, where adulteration rather than complete substitution is practiced, detection is more difficult--is practically impossible, in fact, without the aid of a lens or magnifying glass having a power of about fifteen diameters. There are many seeds of trefoil which can scarcely be distinguished from certain rounded seeds of alfalfa. Generally, however, the trefoil seed has a little projection or “beak” on the middle line of the seed, just back of the scar marking where the seed was attached to the pod. This is rarely found in alfalfa.