278 



THE REStriiTS OF RECENT STUDIES BY ANGOT. 



In 1880 the Central Meteorological Bureau of France, under the 

 minister of public instruction, organized a system of phenological 

 observations; the resulting data have been studied by Angot in a 

 series of memoirs. 



In his first paper (1882) Angot grouped the dates of the wheat 

 harvest as observed during 1880 and 1881 at several hundred stations 

 in France in groups of four or five stations and plotted these upon 

 maps showing the elevations of the stations. By a careful comparison 

 of neighboring stations he shows that the date of ihe harvest is 

 everywhere quite uniformly retarded with increase of elevation, and 

 at the rate of four days in time for every hundred meters of ascent. 

 Apparently this retardation is the general result of a complex sys- 

 tem of influences in which rainfall, drainage, soil, sunshine, tempera- 

 ture, and other local peculiarities combine. It is evident that the spe- 

 cial influence of any local climate on the crop can not be successfully 

 studied until the observations have been corrected for the general 

 influence of elevation. He therefore reduces all the dates of harvest 

 to sea level by applying the preceding correction. 



A similar calculation showed him that the phenomena of flowering 

 are also retarded at precisely the same rate of four days per 100 meters 

 of elevation and these dates also are thus reducible to sea level. 



Angot's charts, showing the dates of flowering and harvesting thus, 

 reduced to sea level, show great regularity and the isanthesic lines 

 show the perfect regularity with which the reduced epoch of flow- 

 ering begins in southern France on the 11th of May and advances 

 nortliward until it reaches the northern boundary of France on the 

 25th of June ; in a similar way the harvesting of winter Avheat begins 

 in southern France on the 10th of June (reduced epoch) and in 

 northern France on the 9th of August. The variations of these 

 isanthesic lines from year to year may be compared Avith the ordi- 

 nary charts of temperature reduced to sea level or with other mete- 

 orological data in a very simple manner. 



Angot has modified and apparently improved the methods of 

 determining the influence of temperature on the date of flowering 

 and harvesting. He says that since 1837 Boussingault's idea that 

 the ripening demands a certain sum total of heat, which is constant 

 for each species of plant, has been generally adopted. At first this 

 sum total w^as calculated by adding together all mean daily tem- 

 peratures from the germination of the seed or the beginning of 

 vegetation after rejecting such means as were below freezing point. 

 Then, as C. H. Martins, De Gasparin, and A. de Candolle had shown 



