376 



SCIENCE 



[N. S. Vol. XXVIII. No. 716 



The theory of Eeibisch (rather than that of 

 Kreichgaur), which the author has chosen as 

 his working hypothesis, was first suggested to 

 its originator as a tentative explanation of 

 certain puzzling geographical facts. In par- 

 ticular is mentioned that the west coast line 

 of South America becomes higher as one 

 proceeds southward from the equator; and 

 that recent coral reefs in the Pacific are partly 

 in the condition of rising and partly in that 

 of sinking. These differences are explained, 

 according to Eeibisch, if in addition to the 

 difference between the rotational and equa- 

 torial diameters of the earth (40 km.), we 

 assume a slow " pendulation " of the globe 

 on an axis approximately perpendicular to the 

 rotational axis, whose poles lie in the vicinity 

 of Ecuador and Sumatra. In consequence of 

 the greater equatorial diameter it follows that 

 as a body of land in pendulation approaches 

 the equator it will tend to be submerged, and 

 that as it approaches the rotational poles it 

 will correspondingly rise. This effect of the 

 swing on land elevation will be greatest along 

 the " Schwingungskreis," a great circle about 

 the earth marking the greatest amplitude of 

 swing. The Schwingungskreis passes through 

 the two rotational poles, traverses the Pacific 

 across its middle, crosses the Scandinavian 

 Peninsula and the continent of Europe south- 

 ward, and lops off the northwest quarter of 

 Africa. In conformity with this theory the 

 terrane quadrant embracing the North At- 

 lantic, Europe, North Africa, and all of Asia 

 except the east third is supposed now to be in 

 "equatorial pendulation," that is, is nearing 

 the equatorial position in the swing on the 

 Sumatra-Ecuador pole. The same quadrant 

 is assumed to have had a position farther 

 northward in the glacial period, and to have 

 lain farther southward in the Jurassic and 

 Cretaceous. The " South Pacific " quadrant 

 likewise is assumed to be now gradually ap- 

 proaching the equatorial position (in " equa- 

 torial phase ") ; while the " North Pacific " 

 quadrant, embracing also the eastern third of 

 Asia, and North America with the exception 

 of Greenland and the Labrador region, is re- 

 ceding from the equator (in "polar phase"). 

 The " Atlantic-India South " quadrant, ta- 



king in the bulk of the Indian Ocean, the 

 south Atlantic, lower Africa, and South 

 America below Ecuador, now finds itself ap- 

 proaching the polar phase. The region of the 

 swing-poles themselves is necessarily subject 

 to little swing, and is therefore supposed to 

 have endured in the course of geologic ages 

 little or no large climatic change. 



In his general introductory discussion, fol- 

 lowing the exposition of the mechanics of the 

 Eeibisch hypothesis, and dealing in a broad 

 way with the significance of pendulation in 

 the origin and distribution of organisms. Pro- 

 fessor Simroth enrolls himself with the ad- 

 herents of the Kant-Laplace theory and takes 

 no account at all of later theories of earth- 

 origin. It is accordingly assumed that life 

 iflust have arisen at a time of average higher 

 temperature than prevails at present. On the 

 question of the place of origin of the first 

 organisms the Eeibisch theory is regarded 

 happily as broad and flexible enough to cover 

 the requirements of any of the various sup- 

 positions that have been made. To the La- 

 placian and pendulationist it need make little 

 difference whether it is held that life arose on 

 land or in the water, at the rotational poles or 

 in the tropics. The hypothesis of a gradually 

 cooling globe, however, favors the supposition 

 of the origin of life at the poles or on the 

 mountains — these being the most cooled situa- 

 tions at any given time after surface solidi- 

 fication. And with further cooling must be- 

 gin the pro-tropical migration, for need of 

 warmth, that in time results in the concentra- 

 tion of a large primitive fauna in the tropics 

 (liberally defined), to form the starting point 

 of the succeeding movements which Professor 

 Simroth finds the pendulation theory so help- 

 ful in explaining. If the " Urthiere " are 

 already there, so much the better. If not, it 

 is scarcely less easy than necessary to get them 

 there, or at least started in that direction. 

 For the companion assumption that the 

 " great bulk of the most ancient known forms 

 of life have lived, first or last, in the tropics, 

 where they arose, or whither they had been 

 driven by the advancing cold," is of cardinal 

 importance in any endeavor to explain animal 

 distribution in accordance with a principle of 



