THE LAWS OF LIVING PROTOPLASM 1 5 



eralizatlon so that the first law to be accepted is 

 what is included in the term biogenesis ( i ) the 

 law that all life is generated from living beings 

 only. 



Chemical Composition of Living Matter. — 

 When life is studied from the chemical point of 

 view the results tell us what chemical bodies are 

 present. No one has been able to write the chem- 

 ical formula for living matter, and after all these 

 years but little is known of the chemistry of living 

 matter. One of the reasons for this lack of chem- 

 ical knowledge is that as soon as a chemical 

 analysis is applied to living protoplasm, it becomes 

 dead. So far as our information goes, it indicates 

 that chemical processes are uniform. However, 

 the very great complexity of chemical reactions in 

 living protoplasm makes it impossible at this stage 

 of our knowledge of the chemistry of living 

 protoplasm to do more than state some of the 

 simpler reactions, see page 41, and to indicate 

 what chemical elements occur in protoplasm. 



There are some eighty-two different chemical 

 elements known to science and not more than 

 twenty-nine of these ever occur In living proto- 

 plasm. Twelve of these are but rarely found, 

 while four are of frequent occurrence. The re- 

 maining thirteen are invariably found and believed 

 to be essential to life. These are hydrogen, car- 

 bon, oxygen, nitrogen, phosphorus, sulphur, 



