1901. Notes. 75 



Influence of Latitude on Plant-Life. 



In the December number of the Geographical Society's Journal is the 

 following notice of experiments made in Germany on the influence of 

 latitude on plant-life : — 



" Prof. Ihne, of Darmstadt sets forth, in the seventh number of the 

 Geographische Zeitschrift, the results obtained as regards the influence of 

 latitude on the dates at which spring is announced by the bursting into 

 flower of various typical trees and shrubs. By the method adopted, 

 which is described at the outset of the paper, the first appearance of the 

 leaf (though recorded in the observations) has not been taken into con- 

 sideration, owing to thegreater difficulty of obtaining a trustworthy record 

 of this than of the dates of flowering, while, given careful observation, 

 the results arrived at may be taken to be the same. Mathematical 

 accuracy is, of course, not to be expected, and the results as a whole are 

 not invalidated by the impossibility of selecting stations at which obser- 

 vations for a sufficient number of years have been carried out, and where 

 other factors besides latitude — longitude, altitude, exposure, soil, &c. — 

 are the same. In his present investigation Prof. Ihne has chosen 

 localities differing as little as possible in these respects. All lie more or 

 less in a line from north to south, the average difference of longitude 

 being only 46 kilometres (28^ miles) ; and from his previous researches 

 into the influence of longitude on the phenomena in question, which 

 showed that for stations of moderate elevation in Central Europe, the 

 advent of spring is retarded by 0.95 day for every in kilometres (60 geo- 

 graphical miles) in an easterly direction, Prof. Ihne shows that such a 

 difference may well be left out of consideration. From the differences 

 observed in the case of eight pairs of stations, which, when reduced 

 to the unit of i° of latitude (in kilometres), show intervals of time for 

 that distance varying from 3.4 to 4.6 days, Prof. Ihne arrives at the con- 

 clusion that for every additional degree of latitude the advent of spring 

 is retarded by about four days." 



There can be 110 doubt that a repetition of these German experiments 

 in other places would be of considerable value, and though Ireland is not 

 so well adapted for the purpose as countries which extend over many more 

 degrees of latitude, it seems to me that we should at least make a trial, 

 and that in our Field Clubs we have an excellent organisation for carrying 

 out this work. By means of our members and their friends scattered 

 throughout the country we should be able to get the results of observa- 

 tions at a large number of places on parallels of latitude at every degree 

 or half degree, for instance, those on a line from Clifden through Tuam, 

 Newtown- Belle w, Auburn, Mullingar, and Dunshaughlin to Lusk, would 

 give statistics for latitude 53° 30', and from these observations we should 

 also perhaps be able to formulate the effects on vegetation of distance 

 from the eastern or western coast line of Ireland. Of course, the obser- 

 vations must be made very systematically, and continued for several 

 seasons, that fair average dates may be obtained, and I hope the Field 

 Clubs will consider this matter worthy of serious consideration. 



G. T. Pl,UNKETT. 



Science and Art Museum, Dublin. 



