Colorimetric determinations of tryptophane by the methods with glyoxylic acid and with vanillin were made on the semen, spermatozoa, and seminal fluid of Holstein bulls. It was pointed out that the latter method was more convenient for the estimation of tryptophane in hydrolyzates of semen and spermatozoa. Furthermore, the samples of smaller amount were sufficient for measuring.
The average values of tryptophane per 100g. of the fresh samples were, semen 141.9, spermatozoa 197.0, and seminal fluid 212.9mg.; these values were, respectively, 1.41, 1.05, and 2. 19 per cent on the dry basis.
The ratio of tryptophane in spermatozoa to that in seminal fluid averaged 1:2.11 on the dry basis.
A rapid method was described for determinig tryptophane in the fresh samples of phys-iological materials. The results of such .a determination were found to agree well with those obtained in the baryta hydrolysates.