Before Aristotle 13 



Such was the character of biological thought within the fifth 

 century, and a generation inspired by this movement produced 

 some noteworthy works in the period which immediately 

 followed. In the treatise Tre/ot r/oo</>?js, On nourishment, which 

 may perhaps be dated about 400 B. c., we learn of the pulse 

 for the first time in Greek medical literature, and read of 

 a physiological system which lasted until the time of Harvey, 

 with the arteries arising from the heart and the veins from the 

 liver. Of about the same date is a work Trept Kapbtrfs, On tb? 

 heart 9 which describes the ventricles as well as the great vessels 

 and their valves, and compares the heart of anin iL- with that 

 of man. 



A little later, perhaps 390 B. c., is the treatise ~pl a-a/wor, 

 On muscles, which contains much more than its title suggests. 

 It has the old system of sevens and, inspired perhaps by the 

 philosophy of Heracleitus (c. 540-475), describes tli- heart as 

 sending air, fire, and movement to the different parts of the 

 body through the vessels which are themselves constantly in 

 movement. The infant in its mother's womb is believed to 

 draw in air and fire through its mouth and to eat in utero. 

 The action of air on the blood is compared to its action on 

 fire. In contrast to some of the other Hippocratic treatises 

 the central nervous system is in the background ; much atten- 

 tion, however, is given to the special senses. The brain resounds 

 during audition. The olfactory nerves are hollow, lead to the 

 brain, and convey volatile substances to it which cause it 

 to secrete mucus. The eyes also have been examined, and 

 their coats and humours roughly described ; an allusion, the 

 first in literature, is perhaps made to the crystalline lens, and 

 the eyes of animals are compared with those of man. There 

 is evidence not only of dissection but of experiment, and in 

 efforts to compare the resistance of various tissues to such 

 processes as boiling, we may see the small beginning of chemical 

 physiology. 



