

1917] CURRENT LITERATURE 423 



author to relate his work to the rather extensive work done on the differential 

 absorption of ions by plant structures and the resulting changes in the reaction 

 of the substratum. 22 This promises explanation of the corrosive action of 

 roots, their great power to absorb salts from soils, as well as their ability to 

 redden neutral litmus. On account of this process some method other than 

 that used by the author will probably need to be employed for investigating 

 acid secretion in natural growth conditions, in the presence of nutrient solu- 

 tions or soil. The value of this work as a basis for a general conclusion is 

 doubtful, considering that only two experiments were performed on a single 

 species, and these in an abnormal condition.— Wm. Crocker. 



I 



Subantarctic and New Zealand floras.— Skottsberg 23 has continued the 

 series of comparisons made between the floras of portions of the southern hemi- 

 sphere characterizing the previous work of Hooker, Diels, Schimper, Werth, 

 Cheeseman, and Chilton, and revising the list of bicentric types by taking 

 recent additions to the flora of Subantarctic America and New Zealand into 

 consideration. The list includes 49 orders. These may be referred to groups 

 ' comprising (1) an Australian and New Zealand element in America, (2) an 

 Andine element in New Zealand and Australia, and (3) an old Antarctic element 

 which is more strictly bicentric. Of the last group Nothofagus is a striking 

 example, with 6 species in New Zealand, 1 in Tasmania, 1 in Tasmania and 

 New South Wales, 1 in New South Wales, and 8 in Chili with 3 extending to 

 Fuegia. 



He includes some recent evidence from fossil plants found in Graham 

 Land, and concludes that there existed an Antarctic Tertiary flora resembling 

 the present floras of Subantarctic America, New Zealand, and Australia, and 

 that the Antarctic continent may have been a center of evolution from which 

 plants and animals wandered north. The present flora is due therefore to a 

 combination of old wanderings, the extinction of certain species during the Ice 

 Age, the survival of others, and finally transoceanic migrations, which, if they 

 ever took place, are still going on. — Geo. D. Fuller. 



Subalpine plants of the Rocky Mountains.— Adding to a series of phyto- 

 geographical papers upon the Rocky Mountain region already noted, 2 * 

 Rydberg 2 * has analyzed the subalpine flora of the region. It consists of about 

 800 species, of which only 10 per cent are entirely restricted to the subalpine 

 zone. About 20 per cent of the whole number are transcontinental plants, 



22 Skene, M., The acidity of Sphagnum and its relation to chalk and mineral salts. 

 Ann. Botany 29:65-87. 1915. 



23 Skottsberg, Carl, Notes on the relations between the floras of Subantarctic 

 America and New Zealand. Plant World 18: 129-142. 1915- 



24 Bot. Gaz. 62:83-84. 1916. 



25 Rydberg, P. A., Phytogeographical notes on the Rocky Mountain region. 

 VI. Distribution of the subalpine plants. Bull. Torr. Bot. Club 43:343~3 6 4. 191 6 



