In the case of a seed stream sampler, the instrument shall take the number of primary samples necessary for the weight of the seed lot being sampled, the primary samples being taken from the seed lot at regular intervals and the resultant composite sample being of a weight not less than the prescribed minimum weight and not greater than can conveniently be reduced by means of one of the methods of sample reduction described in paragraph 30. They shall be installed in such a way that the composite sample can be readily identified with the seed lot from which it was taken.