THE GENERAL CONDITIONS OF LIFE 303 



Omne viviim e vivo this proposition has never experienced an 

 exception. 



The consequences following from this idea are very interesting. 

 If life upon the earth has never been derived from lifeless, but 

 always from living substance, life must have existed Avhen the 

 earth was still an incandescent body. In fact, Preyer so con- 

 cludes. He is, therefore, obliged to give to the conception of life 

 a considerably wider scope than usual ; and to regard as living not 

 only present living substance, but also the incandescent liquid 

 masses as they existed at one time in place of protoplasmic 

 organisms. " If, however, we free ourselves," says Preyer, " from 

 the wholly voluntary and really improbable thought that only 

 protoplasm of the quality existing at present can live, and from 

 the old prejudice, which is sustained simply by convenience, that at 

 first only the inorganic existed, then we will not shrink from the one 

 great step further, we will lay aside spontaneous generation and 

 recognise that vital motion has had no beginning. Omne vivum e 

 vivo ! " 



In accordance with these considerations, Preyer sketches some- 

 what as follows the picture of the derivation of life upon the 

 earth. Originally the whole molten mass of the earth's body was 

 a single giant organism. The powerful movement that its sub- 

 stance possessed was its life. When the earth's body began to 

 cool, the substances that could no longer remain in the liquid 

 state at that temperature, as, e.g., the heavy metals, were separated 

 out as solid masses, and, since they no longer had a share in the 

 vital movements of the whole, formed dead, inorganic substance. 

 Thus arose the first inorganic masses. This process continued. 

 It is remembered that at first hot, molten masses represented the 

 life of the earth. " When in the course of time these compounds 

 became solidified upon the surface of the globe, or, in other words, 

 died, compounds of the elements that thus far had remained still 

 gaseous and liquid appeared, and these became gradually more 

 and more like protoplasm, the basis of the living substance of the 

 present day. With the decrease of temperature and the lessened 

 dissociations there must constantly have appeared more complex 

 compounds, chemical substitutions, denser bodies, and more in- 

 volved and correlated movements of the parts which were being 

 massed closer together. Thus, the first forms of plants and 

 animals, resembling one another and made possible by advancing 

 differentiation, were able to exist." 



" We do not say, therefore, that protoplasm as such existed 

 from the beginning of the earth's formation ; or that without 

 beginning it wandered as such from elsewhere out of space to the 

 cooled earth ; or, still less, that without life it became compounded 

 upon the planets out of inorganic bodies, as spontaneous generation 

 would have it ; but we maintain that the movement that exists in 



