1920] CURRENT LITERATURE 95 



not occur under aseptic conditions. The amount of ammonia apparently may- 

 increase as organisms reduce the toxicity. The ammonia is assumed in this 

 case to exist in delicate transition stages detected by analysis, but not in toxic 

 form. The soils heated above 250 C. are supposed to be less toxic because 

 much of the ammonia is volatilized by the high temperatures. 



The author believes that heating to very high temperatures does not change 

 the quality of the effects gained by heating at ordinary sterilizing temperatures, 

 but merely makes these effects more marked by quantitatively intensifying 

 them. His results, therefore, are valuable in elucidating the effects of sterilizing 

 soils by heat. — Wm. Crocker. 



Vegetation of an antarctic island. — Lying 600 miles southwest of New 

 Zealand, 920 miles southeast of Tasmania, and 970 miles from the antarctic 

 continent, Macquarie Island is in a position of great isolation. It is little 

 more than a short range of mountains with peaks ranging from 900 to 

 1424 ft. in height, the length of the island being 21 miles and its breadth less 

 than 4 miles. The hills descend rapidly toward the sea, forming bold head- 

 lands and precipitous cliffs with no harbors or sheltered bays. It possesses a 

 remarkably equable temperature, the mean maximum being 43° 5 F. and the 

 mean minimum 37^9 F., while the extreme range is only 25^8 F. A rainfall 

 of 45 inches is distributed so that no month has less than 3 inches. Wind 

 velocity is uniformly great, averaging 18 miles per hour. 



It has an impoverished vascular flora of 30 seed plants, 3 ferns, and 1 

 lycopod. Concerning the origin and affinities of this flora, Cheeseman" 

 decides that with the exception of 3 endemic grasses it dates back no farther 

 than the last glacial epoch. Its repopulation was probably affected through 

 the agency of birds, as half its species are common to New Zealand, 15 are 

 found also in Fuegia or South Georgia, and a like number are circumpolar. 



The vegetation is characterized by the entire absence of trees and shrubs. 

 The conspicuous plant forms are the tussock grasses, principally Poa foliosa, 

 the large leaved " Macquarie Island cabbage/' Stilbocarpa polaris, an Aralia- 

 ceous plant resembling a fine rhubarb, the cushion of Azorella Selago, globular 

 mosses often 4 ft. across, and a purple flowered Composite, Pleurophyllum 

 Hookeri, with long sage green leaves. Of these the tussock grass is most 

 abundant, occupying much of the hillside slopes. — Geo. D. Fuller. 



Journal of the Arnold Arboretum. — This new quarterly journal has been 

 established to secure "the prompt publication of information about trees and 

 shrubs collected at the Arnold Arboretum," which was a function of Garden 

 and Forest (1887-1897). The first number (July 1919) includes the fifth paper 

 of Camillo Schneider entitled "Notes on American willows" (pp. 1-32); 



11 Cheeseman, T. F., The vascular flora of Macquarie Island. Sci. Rep. Austra- 

 lian Antarctic Expedition of 1911-14. Series C vol. 7. pt. 3. pp. 63. map. 1919. 



