When a study in biological statistics has advanced so far, that its results are expressed in the form of a frequency table or a variation polygon, we must by no means think that we have attained our end. It is desirable that these results should give us a deeper insight into the biology of our material. In this connection I will not here treat of the coefficients expressing the degree of variability, but only of the conclusions to be drawn from the way in which the frequencies are distributed.