PERIODIC PHENOMENA OF VEGETABLE LIFE. 85 



towards their highest limits is most conspicuous iu Cereals; a 

 consequence is, that the corn in such situations always gives a 

 smaller produce, and an inferior quality, which confirms the 

 statement made by Dove, that in one and the same locality an 

 increased total heat from the flowering to the ripening has a 

 favourable effect on the quality of the grain. In some other 

 plants, fruit-trees for instance, we could not, from the series of 

 observations given, deduce with any certainty the conditions as to 

 the total heat experienced, or the sum of the squares. These 

 relations depend so much on the vital functions of plants, on the 

 physiological and chemical conditions of the formation of their 

 sap and ripening their fruit, that it is as yet impossible to trace 

 out the causes of many variations. 



4. Observations made at separate stations. — (Under this head 

 the original contains eight tables of observations of periodic 

 phenomena of vegetable life made at twenty-nine different stations 

 varying in elevation from 1250 feet to 8400 feet. These separate 

 observations, which form the bases of the general results given in 

 the former part of this article, together with the careful indication 

 of the sources from whence the data they furnish were derived, 

 occupy too much space to be here repeated. It may suffice to 

 give a few general observations which follow.) 



Differences in geographical situation, in exposure, in the 

 direction and form of the valleys, alter so much the period of 

 commencement of the various stages of vegetation, that by a 

 comparison of single stations, whose difference of altitude is not 

 considerable, very great irregularities may be observed. The 

 great local inflections of the isothermal lines, which strike one 

 more especially in the lower parts of the Alps, have been adverted 

 to in a former part of the work. Valleys which are thus warmer 

 than others, of the same or of lower altitudes, have also a cor- 

 responding advance in the development of vegetation. The 

 observations given have enabled us also to follow up the great 

 influence exercised on the periods of commencement of vegetation 



attain a certain age, they are enabled to continue their development for 

 some, time, and will at last remain long after they are reduced to half dried 

 up trunks. 



Von Humboldt published, as early as 1817. observations on the condi- 

 tions of temperature during the period of vegetation of Cereals (Sur les Lignes 

 isothermes ; M e moires d' A rcueil, iii.) G. Lucas communicated observations 

 on the periods of vegetation of winter rye and barley, and the conditions of 

 temperature prevailing at the time at Arnstadt from 1838 to 1848, to Mohl 

 and Schlechtendahl's Botanische Zeitimg, 1849, p. 300. 



