she makes glands and hair; she (as the student's natural aptitude or inaptitude) can prepare the way for and offer resistance to instruction; she is all-sufficient; she produces natural species and legislates language; in disease she may withhold signs, but may be constrained by art to yield them; the means employed by her are likened to the means in use in the arts." 4 One of the Hippocratic treatises, probably dating from the close of the fifth century, gives much zoölogical information, and even suggests something like a classification of animals and plants. Another, somewhat later in date, discusses with great intelligence the generation of animals and plants. It is a worthy predecessor of Aristotle's works upon these matters. 5