A STUDY OF THE HEAD LENGTH VARIABILITY OF EQUINE SPERMATOZOA

The head lengths of horse spermatozoa have been measured in 51 samples and the measurements plotted in frequency distribution curves. These curves are unimodal and their coefficients of variation range from 4.00 to 6 00 (or slightly less). A coefficient in excess of 6.00 indicates an unsound sire, and animals from which skew curves are obtained may be regarded with extreme suspicion since they are not obtained in the case of normal animals. Generally the findings are in harmony with cytological data available, but both require further study before they can be reduced to a systematic basis.