THE ORIGIN OF LIFE 493 



known of the physico-chemical properties of matter a^ it is now 

 found. According to one such theor>-, protoplasm may have 

 originated under conditions of great heat. The general hypothesis 

 is of an origin in a natural course of events, and henc€ one that is 

 open to scientific examination. 



Certain facts of biological knowledge have a bearing in this 

 connection. In the first place, hA-ing organisms are not now known 

 to originate by any such " natural " or spontaneous process, but 

 only from preexisting protoplasm, by growth, or by the detach- 

 ment of parts that occurs in reproduction. Up to the present day, 

 all theories of " spontaneous generation " have failed to be sub- 

 stantiated icf. p. 202). This does not support the idea that 

 protoplasm could have been so produced in the past. It can be 

 claimed that conditions in the past, although natural, were not 

 like those of the present. This may seem to beUe the scientific 

 presumption of the constancy of Nature, but it is a possibihty that 

 may be given consideration. In this connection one may consider, 

 for example, the geological indications that the earth's atmosphere 

 was more suited to support certain forms of plant life during the 

 Carboniferous Period (cf. Fig. 259), than at a later time. There 

 is, however, one way in which evidence corroborative of the 

 Naturalistic Theon,- of the origin of organisms might be obtained. 

 If the biologist is ever able to produce protoplasm under the arti- 

 ficial conditions of laborator>' experimentation, it will not be unrea- 

 sonable to suppose that such a process might have occurred in the 

 remote past, even though it does not occur naturally in the pres- 

 ent. There is, however, small likelihood that an artificial produc- 

 tion of the living substance will be reaUzed in the near future, 

 although it is not an impos-sibility. 



Place of Origin. — As to the place or places in which organisms 

 may have originated upon the earth, it has usually been assumed 

 that they existed first in water, and hence in the primitive oceans. 

 The seas were formed, according to the theories of Geolog>% when 

 the atmosphere began to be differentiated from the hydrosphere, or 

 watery covering of the globe. Presmnably. the first oceans were 

 boiling hot, and the land was, at the same time, the scene of great 

 volcanic action. For a long time, therefore, protoplasm, as we 

 know it. could not have existed. As coohng progressed and condi- 

 tions became more favorable, the seas may have teemed with U\-ing 

 beings before the land became ripe for habitation. There are 



