Biedl showed that the adrenal cortex is essential for life. His classic work shows the rapid development of the knowledge concerning endocrinology. In 1890 there were few publications dealing with internal secretion, but Biedl, in the second edition of his book, 1913, was able to include a bibliography of 8,500 items. The 4th edition (1922) includes an exhaustive bibliography. An English translation appeared in 1912.