Science: Sex Life of Achlya

The existence of sex hormones is one of the most widely-known discoveries of modern biology. Androsterone and testosterone make a man manly, progesterone and estrone make a woman womanly. But in man and other highly evolved animals, the ordinary processes of life depend on other hormones which are non-sexual—such as insulin, the sparkplug hormone from the pancreas. Growth, according to the Carnegie Institution's Oscar Riddle, is due to a combined action of two pituitary hormones, prolactin and thyrotropin.

Growth hormones have been discovered in plants. The major ones are "Auxin A," "Auxin B" and "Heteroauxin." Academic research on plant-growth hormones, mainly done...

Want the full story?

Subscribe Now

Subscribe
Subscribe

Get TIME the way you want it

  • One Week Digital Pass — $4.99
  • Monthly Pay-As-You-Go DIGITAL ACCESS$2.99
  • One Year ALL ACCESSJust $30!   Best Deal!
    Print Magazine + Digital Edition + Subscriber-only Content on TIME.com

Learn more about the benefits of being a TIME subscriber

If you are already a subscriber sign up — registration is free!