December 25, 1908] 



SCIENCE 



907 



turbanee may be attended by electrical 

 passages between the saline water-bodies 

 and the land tracts. There are reasons for 

 believing that electrical interchanges were 

 more active in the growing stages of the 

 earth than at the present time when the 

 solar system may be presumed to have 

 settled down into a condition nearer equi- 

 librium. The planetesimal matter circu- 

 lating about the planetary nucleus and the 

 sun, and between them, probably served 

 both to disturb the electrical status of these 

 bodies and to afford a means of electrical 

 communication between them and the 

 planetesimals. Under electric laws, plan- 

 etesimals charged with electricity and cir- 

 culating at high velocities about the young 

 planet should have had the effect of elec- 

 trical currents, and should have generated 

 magnetic fields about the magnetizable mat- 

 ter of the earth ; and these magnetic fields, 

 in turn, should have modified and perhaps 

 controlled the paths of electrons and ions 

 traversing these fields. It is beyond the 

 scope of this paper to try to follow these 

 into detail, and it may suffice to merely 

 indicate that electrolytic action stimulated 

 by electrical currents traversing the surface 

 may fairly be presumed to have played a 

 more active part during the nebular stages 

 than they do to-day, whatever that part 

 may be. 



On similar grounds, it may be suggested 

 that the agitations of radioactivity, and the 

 states of ionization to which it gives rise, 

 may have played a slightly more active 

 part in the chemical processes of early 

 times than they do to-day, whatever that 

 may be, because of secular decay. 



Some suggestions respecting the original 

 localization of terrestrial life may be de- 

 rived from a study of the localizations of 

 to-day. The more primordial types of the 

 vegetal life of the mid-ocean are limited in 

 variety and in susceptibility to variation. 



In the judgment of some of our most 

 trusted botanists, pelagic vegetal life does 

 not present pronouncedly the qualities 

 which imply germinal or evolutionary 

 power. A similar statement may be made, 

 with qualifications, relative to the life of 

 the larger fresh-water bodies. In the shore 

 tracts, indeed, there is greater variety of 

 life and greater indication of germinal com- 

 petency, but even here the forms which lie 

 nearest the hypothetical primitive types do 

 not give signs of conspicuous evolutional 

 potency. On the other hand, the plant life 

 of the land presents much greater variety 

 of form and of organization, and greater 

 signs of germinal virility. 



If we may judge of the fitness of soils 

 to serve as a nidus of organic genesis, by 

 the life it fosters to-day, a favorable ver- 

 dict seems warranted by the remarkable 

 assemblage of low forms which make the 

 soil their habitat and which manifest 

 peculiar adaptations to their earthy condi- 

 tions and to one another. There are not 

 only a host of simple forms in which photo- 

 synthesis plays its usual part, but forms 

 that flourish quite irrespective of sunlight; 

 there are not only species that use carbon 

 dioxide and require oxygen, but species that 

 live quite without free oxygen, and even 

 find it a hostile element; there are forms 

 that oxidize sulphuretted hydrogen and use 

 the energy thus derived for their activities, 

 and there are forms that oxidize ferrous to 

 ferric iron to like ends.^^ Some of the sul- 

 phur-bacteria seem to combine the genera- 

 tion of energy from sulphuretted hydrogen 

 with the more common mode of oxidizing 

 carbon compounds, thus uniting in a sug- 

 gestive way independent chemical processes. 

 There are also bacteria that oxidize free 

 nitrogen into nitrites and others that pro- 

 mote the formation of nitrates. The rich 



" Jost's " Plant Physiology," Gibson's transla- 

 tion, 1907, pp. 220-31. 



