Febbuaey 22, 1907] 



SCIENCE 



289 



discusses the methods of such study, and 

 a classification of the physiological proc- 

 esses for purposes of investigation, through 

 the four critical periods of the plant's life 

 history, germination, orientation of seed- 

 ling, spread of adult, and fruiting or spori- 

 fication. 



The Vegetation of the Blue Mountains of 

 Jamaica: Dr. Forrest Shreve, Woman's 

 College, Baltimore. 



The Blue Mountains of Jamaica above 

 5,000 feet altitude in the neighborhood of 

 Cinchona, the Tropical Station of the New 

 York Botanical Garden, are covered by 

 evergreen broad-leaved forest. Floristi- 

 eally the area is related to the surround- 

 ing tropical lowlands and to Eastern North 

 America. In vegetative characteristics the 

 forest likewise shows a blending of tropical 

 and temperate features. The climate is 

 one of much rainfall and high humidity. 

 Alpine influences are but weakly operative 

 at the highest altitudes. Local differences 

 in the vegetation can be correlated with the 

 topography and its determination of 

 several of the physical factors. Bry- 

 ophytes and Pteridop bytes, as well as epi- 

 phytes, are abundant. There is a marked 

 difference in humidity, light, wind and 

 other factors between the forest floor and 

 the forest canopy, with a corresponding 

 contrast between the hygrophilous char- 

 acter of the terrestrial herbaceous vegeta- 

 tion and lower epiphytes, and the xerophi- 

 lous character of the higher epiphytes and 

 the foliage of the trees. The winter is 

 relatively a season of rest in leafing and 

 flowering, the spring and summer the sea- 

 sons of greatest activity. Growth of 

 leaves and shoots is extremely slow even in 

 the most rapid growing forms. Transpira- 

 tion is high under favorable conditions, but 

 shows a high degree of sensitiveness to 

 changes in temperature and humidity, and 



under the climatic conditions commonly 

 prevailing is very low. 



Cultures of TJredinem in 1906: Professor J. 



C. Arthur, Purdue University. 



The experimental study in the life his- 

 tory of various species of plant-rusts, of 

 which this paper is a report, has been in 

 progress during the last eight years. It 

 embraces rusts of economic importance, 

 and others as well. The most notable re- 

 sult of the present year was with flax 

 rust, which is very destructive in the flax 

 fields of the northwest. It was found that 

 this rust, unlike most of its near relatives, 

 produces all its stages upon the flax plant, 

 and that infection comes from the old 

 straw and stubbles that have laid out of 

 doors through the winter. The common 

 rust on Juncus tenim was found to be con- 

 nected Math the Mcidium on Silphium, and 

 the Uromyces on Scirpus fltwiatilis, with 

 the Mcidium on Gicuta macidata. Con- 

 siderable advance was made in separating 

 the Carex rusts; and a number of Lepto- 

 puccinia were also grown. The Avork was 

 aided by a grant from the society, and was 

 in charge of Dr. E. W. Olive. 



Peridermium acicolum the JEcial Stage of 

 Coleosporium Solidaginis: Dr. G. P. 

 Clinton, Connecticut Agricultural Ex- 

 periment Station. 



Peridermium acicolum was found abun- 

 dant on Pimis rigida at South Manchester, 

 Conn., during the spring of 1906. It has 

 been found in four different places in Con- 

 necticut—but has been reported only four 

 or five times outside of the state, its dis- 

 tribution so far being confined to a small 

 area extending from Massachusetts to New 

 Jersey. After considering the synonomy 

 in detail, the writer follows Arthiir and 

 Kern in calling the rust Peridermium 

 acicolum (Und. & Earle). Prom observa- 

 tions made at South Manchester, verified 



