600 



SCIENCE. 



[N. S. Vol. III. No. 



present flora, enumerated at 386 species by 

 Lange, contains a slightly larger number of 

 European than American species. Warming 

 finds two botanical regions, of which the south- 

 ern is characterized by the presence of the white 

 birch, extending two degrees north from Cape 

 Farewell, and contains many European types. 

 The larger, or northern, region is more American 

 in its facies, but the majority of the plants are 

 circumpolar. Most authors have regarded this 

 flora as of Scandinavian origin ; but the sug- 

 gestion is here made of the possibility of its 

 being merely the wreck of the earlier Tertiary 

 development. The Greenland flora is essen- 

 tially that of the highest White Mountain sum- 

 mits. 



All these and other details concerning the 

 physical features of Greenland help us to im- 

 agine the condition of things over our northern 

 regions in the ice age. Greenland must have 

 had a gi-eater development of ice in former times, 

 since the present habitable strip of land is glaci- 

 ated ; but the authors believe it was milder 

 there in the times of the early Norse settlements 

 several hundred years ago. The d6bris in 

 Greenland is principally transported in the 

 lower part of the glaciers, whence it is possible 

 to believe in a similar movement for the material 

 of the drumlins and many boulders. The 

 Greenland ice moves more rapidly than the 

 Alaskan and Alpine glaciers, averaging about 

 fifty feet daily. This may be due partly to the 

 steeper slopes, which are from 100 to 200 feet 

 per mile. Inclinations of fifty feet to the mile 

 are necessary for vigorous movement ; but a 

 large part of the American ice did not possess 

 surface slopes of more than twenty-five or 

 thirty feet to the mile. 



Attention is paid to the great elevatory 

 movements of our continent upon both the 

 Atlantic and Pacific coast, as well as on the 

 Gulf of Mexico, which took place in pre-glacial 

 times — from 2,000 to 3,000 feet in amount — and 

 it is thought this uplift has been suiBcient to 

 develop the severe glacial climate. The astro- 

 nomical theories, including the latest views of 

 Croll, Wallace, Drayson, Becker, Sir Eobert Ball 

 and Sir John Evans, are weighed in the bal- 

 ance and found wanting in the comparison. 

 The great uplift would have given rise to a high 



plateau climate with abundant snowfall and 

 accumulation of an ice sheet, whose weight 

 seems to have been a chief cause of the ensuing 

 depression in the Champlain age. 



The distribution of the till, more or less coin- 

 cident with terminal moraines, allows of a classi- 

 fication into stages. 



First came the culmination of the Lafayette up- 

 lift, which is regarded as Quaternary and there- 

 fore not to be esteemed as the equivalent of the 

 Scanian or Norfolkian of Geikie, as they belong 

 to the Pliocene. It includes the Albertan and 

 Saskatchewan stages of G. M. Dawson. Next 

 came the Kansan, Aftonian and lowan stages, 

 all of the four named being classified as the 

 Glacial epoch proper. The second epoch is 

 named the Champlain, being the time of melting 

 and of subsidence, and is divided into the Cham- 

 plain marine beds, the Wisconsin drift sheet in- 

 dicating moderate reelevation, the Warren 

 glacial lake, the Toronto stage of temperate 

 climate, the Iroquois lake and the St. Lawrence 

 lake, overflowing through the Champlain basin 

 into the Hudson river. The number of stages 

 agrees exactly with those specified by Geikie for 

 Europe, provided the Lafayette consist of two. 

 The authors rank themselves as advocates of 

 the unity of the glacial epoch. It is probable 

 that the present diverse schools of glacialists 

 will tend hereafter to a greater convergence 

 than divergence. C. H. Hitchcock. 



Hansen's Studies in Fermentation. Practical 

 Studies in Fermentation, being contributions 

 to the Life History of Micro-organisms. By 

 Emil Christian Hansen, Ph. D., Professor 

 and Director of the Carlsberg Physiological 

 Laboratory, Copenhagen. Translated by 

 Alex. K. Miller, Ph. D., F. I. C, F. C. S., 

 and Revised by the Author. E. & F. N. Spon, 

 London and New York (12 Courtland St.), 

 1896. Pp. xiv+277. 8vo. Illustrations. 

 Cloth. 



The general features of Dr. Hansen's reform 

 in the fermentative industries have long been 

 known to every one who is interested in the 

 scientific and practical features of applied my- 

 cology. They are known as new and important 

 departures in regard to method and application, 

 and as important factors in the evolution of 



