Forty-five samples of seminal plasma obtained from eight boars and seventeen samples of vesicular secretion collected from individual boars had mean zinc contents of 22·7 and 137·4 μg/ml, respectively. It was concluded that most of the zinc present in the seminal plasma of the boar is derived from the vesicular secretion.
The mean concentrations of the organic constituents studied were:
Seminal plasma: total nitrogen 4·42 mg/ml (non-dialysable 88·7%), citrate 1·28 mg/ml.
Vesicular secretion: total nitrogen 15·1 mg/ml (non-dialysable 93·9%), citrate 6·07 mg/ml, fructose 0·557 mg/ml, galactose 0·092 mg/ml.
In both seminal plasma and vesicular secretion, the concentration of zinc was positively correlated with that of total and non-dialysable nitrogen and citrate. The correlation with nitrogenous substances was particularly strong in the seminal plasma of individual animals and there was evidence from the partial correlation coefficients that these associations were independent of the zinc-citrate relationship. However, fructose and galactose which do not have an appreciable affinity for zinc under physiological conditions also showed significant positive correlations with zinc (in vesicular secretion) and most of the organic constituents were interrelated in this way, indicating that in such data the influence of chemical combination may be masked by that of other factors which regulate the composition of these fluids.