ZOOLOGY AND BOTANY, MICUOSCOPY, KTU. 89 



her own methods of work. The species she examined were R. calicaris, 

 R.fraxinea, R.fastigiata, and R. pollinaria. She finds that the attach- 

 ment organs are strands of closely- woven hyphaj longitudinally arranged, 

 and continuous with the cortical tissues. They penetrate the periderm 

 by cracks or lenticels, and by wedge action cause extensive splitting. 

 New plants arise from the horizontal branches of these strands. She 

 finds that the Hving tissues of the tree may be penetrated and injured. 

 She also found evidence to prove that hypertrophy of the peridermal 

 tissue of the host arises, and erosion of the wood by ingrowths of hyper- 

 trophied tissue. Methods of clearing the trees from lichen growths are 

 su": crested. 



DO 



Varenne Collection of Lichens.* — This collection formed part of the 

 herbarium of the late E. G. Yarenne, who died in 1<S87. R. Paulson has 

 made a systematic study of the lichens, which amount to 440 specimens. 

 He has verified the determinations, and renamed them according to 

 modern requirements The Essex lichens among them, to the number 

 of 124, form a nucleus for a lichen flora of the county. They are now 

 in the possession of the Essex Field Club. 



Lichens of Whatcom County, Washington.f — A. C. Herre gives a 

 descriptive and ecological account of the county, as well as of the lichens 

 found there. Originally the district was covered by typical dense coni- 

 ferous forest, but intermingled with the Conifers are various deciduous 

 trees, especially on low ground. Lichens are less prominent a feature 

 in the region than mosses and hepatics ; there are practically none of the 

 very large species, but crustaceous forms on rocks, soil or trees are fairly 

 abundant. 



Notes on Parmeliopsis.iJ: — L. W. Riddle writes a full description of 

 all the plants of this genus (or section of Parmelia). He gives a 

 careful historical account of eich species, and bases his conclusions on 

 his examination of types as far as possible. The species occur in 

 America as well as in Europe, and all have the same habitat — old fence- 

 rails and the bark of Conifers. 



Lichen Ecology. § — In discussing the ecology of the Foothills vegeta- 

 tion of the Rocky Mountains, A. G. Vestal includes lichens as an 

 Association ; the ^■arious members of the Association have been deter- 

 mined and described by R. Heber Howe. The rocks are dry surfaces 

 much exposed to sun and wind, and they are first invaded by primitive 

 xerophytic stages of fine-grained criistose species, notably the black- 

 grey Rmodina radiata ; coarser species follow, and later Parmelia 

 conspersa becomes established as the dominant lichen. Notes on moist 

 surface lichen species are also given. 



* Essex Naturalist, xviii. (1917) pp. 133-4. 

 t Bryologist, xx. (1917) pp. 76-84. 

 X Brvologist, XX. (1917; pp. 69-76 (1 pi.). 

 § Bat. Gaz., Ixiv. (1917) pp. 360-2 (1 fig.). 



