824 THE POPULAR SCIENCE MONTHLY. 



were narrowing at that time toward the north, and that their ex- 

 tremities were pointing toward some spot in the vicinity of what 

 is now the Bering Strait, in the same way as South America, 

 South Africa, and South Australia are now pointing toward the 

 south pole. The great plateau of northeast Asia, which has re- 

 mained a continent ever since the Devonian age, has so much the 

 shape of South America pointing northeast that the resemblance 

 is simply striking.* On the other side, we know that the Mio- 

 cene flora discovered in Greenland, Spitzbergen, and New Siberia 

 indicates the existence of a great Miocene continent where we now 

 have but the ice-clad arctic archipelagos. So that we must con- 

 clude that, while the central (temperate and equatorial) parts of 

 the globe really offer a certain permanence in the disposition and 

 general outlines of their continents, the arctic region stands in a 

 different position. It was under the ocean during a large part of 

 the Secondary period, it emerged from the ocean and was occu- 

 pied by a large continental mass during the Tertiary period ; and 

 now it is again under water. Such being the conditions of the 

 arctic region, we may suppose that the same oscillations took 

 place in the antarctic region as well. In such case, the two cir- 

 cumpolar regions would have been periodically invaded by the 

 ocean (either alternately or during geological epochs closely fol- 

 lowing each other), and they would have periodically emerged 

 from the sea in the shape of continents more or less indented by 

 gulfs and channels. In short, a certain stability in the distribu- 

 tion of land and water in the equatorial and temperate zones, and 

 unstability in the circumpolar regions (with, most probably, an 

 unstable Mediterranean belt), would perhaps better express the 

 observed facts than a simple affirmation of stability of conti- 

 nents. If these considerations prove to be correct and I venture 

 to express them only as a suggestion for ulterior discussion then 

 the hypothesis of a former more or less close land-connection be- 

 tween the southern extremities of our present continents would 

 not appear unlikely, and the striking similarity between the fau- 

 nas of Patagonia and Australia would be easily accounted for. 



in. 



Few branches of science have developed with the same rapidity 

 as bacteriology during the last few years. The idea that infec- 

 tious diseases are due to some micro-organisms invading the body 

 of the infected animal is certainly old. It was ventilated many 



* Petermann's and Habenicht's map of Asia, in Stieler's Hand Atlas (No. 58), shows 

 this shape of the plateau better than any other map. For more details see my map in the 

 Orography of East Siberia, in the Memoirs of the Russian Geographical Society, 1875, vol. 

 v (Russian). 



