Dr. Cavazzi of Bologna has a method which is a variant of that of testicular extract injection. Cavazzi says that Brown-Séquard's original method of opotherapy failed, not because it was wrong in principle, but because he had used an extract that did not and could not contain the active endocrine substances. The testicular hormones (like other hormones) pass directly into the efferent blood,. according to the exact conception of an internal secretion as enunciated by Claude Bernard.
The author therefore used the serum of testicular efferent blood from young and healthy animals, as this, he declares, must contain the testicular hormones. According to Cavazzi, the species of animal is a matter of indifference, because the efficacy of the hormones is a chemical matter. A number of old men were treated both at Bologna and in Paris. Cavazzi says that all were greatly improved. He believes that the phenomena of "rejuvenation"