LIVING SUBSTANCE 121 



turn that this origin of organic out of inorganic substance is pos- 

 sible only with the help of living organisms ; Preyer ('80) has said 

 that organisms are distinguished from inorganic bodies by the fact 

 that they always presuppose the existence of living substance. 

 Only in this form does the distinction hold good, at most, for the 

 present time. Virchow's dictum, " Omnis cellula c cellula," which is 

 the generalisation that has become necessary in the course of time 

 from the old dictum of Harvey, " Omne vivuvi ex ovo," holds good 

 only for the conditions that now prevail upon the earth's 

 surface. If we go backward in the development of the earth, 

 we soon come to a time when the earth was an incandescent mass, 

 upon which no cell could exist. Cells must, therefore, have 

 arisen at .some time from masses of matter that were not cells. 

 At this point the following alternative is presented : Either, as 

 the theory of spontaneous generation assumes, organisms have 

 arisen at some time out of inorganic substances, or. as the theory 

 of the continuity of life demands, the conception of life must be 

 applied also to those bodies from which cells have developed, 

 although they were totally different from the living substance of 

 present organisms. If the former be accepted, the difference in the 

 derivation of the two groups of bodies disappears of itself, for then 

 not only inorganic, but also organic nature is derived from non- 

 living substance. Preyer decides upon the second assumption ; 

 he considers as living the mass of matter out of which cells 

 have developed, and even the whole incandescent mass of the 

 earth itself; and he extends still further Harvey's dictum to 

 " Omne vivuvi c vivo," therebj" expressing the idea that life has 

 never originated, but has existed from eternity. But the difficulty 

 of establishing a fundamental difference between organisms and 

 inorganic bodies upon the ground of their derivation is not 

 thus set aside. For, in harmony with his idea that the whole 

 incandescent mass of the earth is to be considered as living, 

 Preyer assumes that the inorganic has arisen out of the organic. 

 Hence, not only does organic nature, but also inorganic, pre- 

 suppose the existence of living substance, and it is clear that 

 the above-mentioned difference in the derivation of the two great 

 groups of matter disappears. It is seen, therefore, that even by 

 such an extension of the conception of life as Preyer's the difference 

 in derivation cannot b<_' maintained for the earlier period of the 

 earth's development. 



Just as little absolute difference exists between the organism 

 and the inorganic body in their development as in their repro- 

 duction and derivation from like bodies. By development is 

 understood a series of changes undergone by the new-born 

 organism, which make it finally like its parents. Such changes 

 occur in inorganic nature likewise, and are there not funda- 

 mentally different from those in nr^anisms. Ji.ff., if a piece of 



