THE QUANTITATIVE ASSAY FOR THE TESTICULAR HORMONE BY THE COMB GROWTH REACTION

¹ From the Department of Physiological Chemistry, University of Chicago, Chicago

A quantitative study of the comb growth reaction in capons to the testis hormone leads to the following conclusions:

1. There are marked individual variations in the responses of Brown Leghorn capons to the testis hormone.

2. Age and weight of the birds and the initial size and shape of the combs of the capons are not determining factors in this variability in responses.

3. Daily injections over five days yield better quantitative data than longer injection periods.

4. It is best to determine the minimal dose causing in five days with daily injections, an increase of 3 to 7 mm. in the height and length of the comb

5. A bird unit is defined as the amount of the hormone which, when injected daily for five days, yields an average of 5 mm. increase in length and height of the combs of at least 5 Brown Leghorn capons.

6. The light factor discovered by Womack, Koch, Domm and Juhn must be taken into consideration in accurate assays.