SOME (iHEAT NAMES IX BIOUHJY 



309 



Life comes from Life. Another group of men, after years of 

 patient experimentation, worked out the fact that life comes from 

 other life. In ancient times it 

 was thought that life arose 

 spontaneously; for example, 

 that fish or frogs arose out of 

 the mud of the river bottoms, 

 and that insects came from the 

 dew or rotting meat. It was 

 believed that bacteria arose 

 spontaneously in water, even 

 as late as 1876, when Professor 

 Tyndall proved by experiment 

 the contrary to be true. 



As early as 1651 William 

 Harvey, the court physician of 

 Charles I of England, showed ^ &* g^ p 



that all life came from the egg. 



Tt was much Inter however Prof. Tyndall 's experiment to show that if 

 was ! > JNvever, nir nnntnl - ni - no . aprTriB ; Q u. PT , t frnrn nr _ 



that the part played by the 

 sperm and egg cell in fertiliza- 

 tion was carefully worked out. 

 It is to Harvey, too, that we 

 owe the beginnings of our 

 knowledge of the circulation 

 of the blood. He showed that 

 blood moved through tubes in the body and that the heart pumped 

 it. He might be called the father of modern physiology as well 

 as the father of embryology. A long list of names might be added 

 to that of Harvey to show how gradually our knowledge of the 

 working of the human body has been added to. At the present 

 time we are far from knowing all the functions of the various parts 

 of the human engine, as is shown by the number of investigators 

 in physiology at the present time. Present-day problems have 

 much to do with the care of the human mechanism and with its 

 surroundings. The solution of these problems will come from ap- 

 plying the sciences of hygiene, preventive medicine, and sanitation. 





air containing germs is kept from or- 

 ganic substances, such substances will 

 not decay. The box is sterilized; like- 

 wise the tubes (t) containing nutrients. 

 Air is allowed to enter by the tubes (w), 

 which are so made that dust is pre- 

 vented from entering. A thermometer 

 (th) records the temperature. The sub- 

 stances in the tubes do not decay, no 

 matter how favorable the temperature. 



