Methods for quantitative determination of proteolytic, lipolytic and haemolytic activities and egg yolk factors in semen are described. 2. Comparative quantitative determinations of these enzyme activities in the semen of goat, ram, bull, boar, dog and horse have been carried out. 3. Special interest attaches to the egg yolk turbidity factor which is found in goat semen and, in small concentrations, also in boar semen. 4. As each species appears to have its specific enzyme pattern, regular enzymatic control does not seem to have great significance.
