PROTOPLASM, LIFE AND DEATH 183 



ing protoplasm as the substance in us and other organisms 

 which " lives." Death consists in the destruction the 

 chemical undoing or decomposition of protoplasm. 1 In 

 simple microscopic unicellular animals and plants, this is 

 obvious so long as the protoplasm retains its chemical 

 structure it is not " dead." Thus, it is possible with 

 many small simple organisms such as animalcules and 

 the seeds of plants to dry them, and to expose them 

 to extreme cold, and to deprive them (by aid of a vacuum 

 pump) of all access of free oxygen or other gases. All 

 chemical change is thus necessarily arrested. But the 

 atomic structure of the chemical molecules in the proto- 

 plasm is not destroyed. Sir James Dewar, M. Becquerel, 

 and others have shown this by most carefully conducted 

 experiments. Seeds of clover, mustard, and wheat so 

 treated do not " die " ; the mechanism remains intact, and 

 when, after many weeks, the seeds are moistened, warmed, 

 and admitted to contact with the atmosphere, the mechan- 

 ism again begins to work, the protoplasm resumes its 

 activity, the seed " sprouts." Similarly Dewar has shown 

 that bacteria are not killed by extreme cold, the tempera- 

 ture of liquid hydrogen. When thus frozen they remain 

 inert but are even in this condition liable to be " killed " 

 by exposure to the blue and ultra-blue rays of sun- 

 light ! Life was defined by Herbert Spencer as " the 

 ' continuous ' adjustment of internal to external relations," 



1 Protoplasm is not a single chemical compound ; it is the name 

 given to the soft, slimy substance of cells, and contains many chemical 

 compounds proteids, fats, and others ; some on the way to assume 

 greater chemical complexity ; others in process of destruction. The 

 critical highest chemical body concealed in protoplasm has no gener- 

 ally recognised name. It is a proteid-like body, consisting chiefly of 

 carbon, oxygen, hydrogen, and nitrogen, with some saline con- 

 stituents. This is the real ultimate " living matter," and I suggested 

 in the Encyclopedia Britannica (article Protozoa) in 1886 that it 

 should be called " plasmogen." 



