XVII. 



SOME EMPHATIC PROBLEMS OF CLIMATE 

 AND PLANTS. 



Speculative Notes Upon Phenology.' 



1. The Physiological Constant. — There are deeper 

 questions involved in the study of the periods of plants 

 than the mere pageant or moods of the seasons. We 

 must determine how it is that climate superintends 

 the periods of plants, or, at least, which one of its 

 many attributes is most intimately and uniformly asso- 

 ciated with the periodical phenomena of life. We shall 

 then be able to establish a physiological constant, by 

 means of which climate and life -events can be studied 

 and compared. In the first place, it may be well to ask 



• Extract from " Some Suggestions for the Study of Phenology," prepared for 

 the Weather Bureau, United States Department of Agriculture, hut yet un- 

 published. The report has considered a long array of records of phonological 

 phenomena, — such as dates of blooming, leafing, and the like, — and has dis- 

 cussed how these records are influenced by latitude and altitude, and has drawn 

 various conclusions from them. It has also presented the merits of such records 

 as a means of recording meteorological phenomena. It now conies to the con- 

 sideration of those deeper problems of the inter-relations of plants and climates, 

 and at this jwint the reader is asked to take up the discussion. He may desire 

 to know that Phenology (contraction of phenomenolng]/) is that science which 

 considers the relationship of local climate to the periodicity of the annual phe- 

 nomena of living things. Its chief recbrds, on the side of organisms, are those 

 of the leafing, blooming and maturation of plants, and the migrations and sea- 

 sonal habits of animals. The report from which this Essay is extracted gives 

 fuller references to the literature of the subject, together with illustrations. 



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