The study of human semen and its importance in assessing the probable fertility of a given marriage has received a great deal of attention in recent years. Unlike blood or urea estimations, semen analysis has no fixed standards of normality. Harvey and Jackson (1945) and Hammen (1944) showed that the criteria of fertility given by earlier workers (Moench and Holt, 1931 ;Hotchkiss, 1936;Lane Roberts, Sharman, Walker, and Wiesner, 1939;Weisman, 1941) were set far too high. More recent work (Falk and Kaufman, 1950;MacLeod, 1951) has shown that excellence in one quality, such as motility, may compensate for poorness in another, such as density. The method used in this laboratory of giving A, B, or C for each semen character and describing the semen in terms of the number of "As" scored does imply compensation, and still proves a useful method of assessment. It has, however, several disadvantages. The categories denoted by each letter cover a wide range of values, and, as always in a discontinuous classification, the difference between A and B may be insignificant if both are borderline values. Neither is there any means of determining how much an A in one character may offset a B or C in another. Probably, however, the greatest disadvantage lies in the impossibility of using such a classification for mathematical processes, even one so simple as determining the mean values of a series of several specimens produced by the same donor.The present work was undertaken with the object of combining the results of semen analysis in a single numerical expression which, in addition to being an estimate of the donor's fertility, could also be used for studying response to treatment, and for classifying semen for purposes of experimental research.
