492 THE THEORY OF EVOLUTION 



became the source of li\'ing things upon our planet has. therefore, 

 never appealed to biologists. 



Another theory- of the origin of organisms is that of Miraculous 

 Creation. As a philosophical concept, one may suppose that the 

 primeval protoplasm arose by some '' creative " act which was 

 " miraculous "' in the sense that it was not a part of the established 

 order of nature. Science can only say regarding this theory that 

 there are no facts which are suggestive of such a process. 



There remains what may be termed the Xaturalistic Theory. 

 Here again, we have only suggestive e^'idence. although it is pos- 

 sible that facts may some time be discovered that will lend more 

 definite support. According to this hypothesis, when conditions 

 became suitable a primitive substance arose, ha\'ing the properties 

 of hfe, though perhaps in a more elementary fashion than any 

 H\'ing bodies that now exist. If such a substance were able to 

 assimilate other matter, with consequent increase in bulk, and to 

 eliminate the end products of its activities, and if portions acci- 

 dentally detached possessed the properties of the original mass, 

 metabohsm and reproduction would occur. If the organization 

 became sufficiently elaborate, such a primitive form of hfe might 

 respond to stimulation in a more complex manner than an^-thing 

 not alive. From such a primeval substance, it is conceivable 

 that protoplasm, organized in the form of the units termed cells, 

 may have arisen. The di\nsion of labor between nucleus and cell 

 body, as it appears in the ceU. would then be regarded as the first 

 great step in the evolutionarA' changes whereby this primeval 

 protoplasm became differentiated into the li\'ing forms of the 

 present day. According to this theon.-, the ceU would not be the 

 Drimitive form of organism, although it is the simplest \-ital unit 

 now recognized. If this speculation is followed a step farther, it 

 may be supposed that the unicellular organisms of the present 

 day have descended from such early cells without evolving beyond 

 the unicellular state, but with much speciaHzation as single cells; 

 while many-celled organisms have arisen by an advance bej'ond the 

 single-celled condition. 



It is not necessar\' to present at this point the detailed specula- 

 tions regarding the manner in which such a union of organic mate- 

 rials, to form a physico-chemical system ha^'ing the characteristics 

 of protoplasm, might have occurred. These speculations are 

 many and varied, but are ob\'iously based solely upon what is 



