NOTES OX RECENT KESEAKCH. 



507 



flourishes, the mode of cure attempted was by inoculation with an anti- 

 toxin, prepared from attenuated cultures of the pest. In other cases it is 

 recommended that the extract of a plant which is naturally immune be 

 injected in place of the antitoxin. 



Analogous prophylactic measures are described in relation to JJacUi/cs 

 l)iLtrefaciens.—J. B. F. 



Ecology. 



Ecolog-y, The Physiogrraphic, of Chicag-o and vicinity ; a study 

 of the Orig-in, Development, and Classification of Plant Societies. 

 By H. C. Cowles {Bot. Gaz. vol. xxxi. p. 13, No. 2 ; p. 145, No. 8).— The 

 author observes that Ecology, or the study of plants in relation to their 

 envu'onment, is now regarded as important, and the present paper is to 

 suggest a classification of a portion of the ecological field. 



Ecology includes the study of the origin and life-history of plant 

 structures, as also of plant societies. 



(1) Climatic factors issue in tropical forests, deserts, prairies, (^c- 

 These suggest an ecological plant geography. (2) Local influences, as 

 soil, slope, light, Sec, or the physiographic nature of a district. 



The climate may be the same, but these factors produce marked 

 changes of themselves. Hence are swamp, dune, forest, river-bluff", &c. 



" Physiographic Ecology." — Plant societies are grouped as hydrophytes, 

 mesophytes, and xerophytes. 



The author observed that while heaths and moors have closely similar 

 .species and vegetative adaptations, their plant societies were often found 

 grading into each other. 



In water-content these societies were ccrij different, the peat-moor 

 or bog being hydrophytic, and heath xerophytic. Hence some factor other 

 than water-content is responsible for both. 



Vegetation of peat-bogs is radically difi'erent fi'om that of river- 

 swamps, which have the same water-con'. cnt. 



While atinosphcric influences (light, heat, air) operate over wide areas 

 and have subordinate local importance, noil influences (including the 

 heat, air, and water in it), as well as chemistry and physics, are of pre- 

 dominant local importance. These depend on surface geology and 

 topography. 



To illustrate the principle of physiographic ecology, the author 

 describes " The Inland Group " of a River series. He commences witli 

 the uppermost ravine at the source of a river, which is deep and narrow 

 through vertical cutting away. Here, if it be clay, the steep sides are 

 almost entirely void of vegetation, because of the instability of the soil 

 and of landslides. Lower down the slopes are less precipitous, iuid the 

 ravine widens more than it deepens, so that a sutticient stability is 

 acquired to permit of a considerable growth of vegetation. .It i^ here 

 that the highest type occurs ; having passed through the lierlwceous and 

 shrubby stages to the highest " mesophytic " forest— a Maple [Acer 

 saccharimom)ionnd associated with Limes [Tilia anierirajia), Ashes, Elms, 

 kc. ; the most characteristic undershrub being the Witch-hazel {ILnuauicU^ 

 virginiana). The herbaceous •i)]ants are vernal forms, c.<j. IL'j)atica, 



y 2 



