LEAFING, rL(nVEllING3 ETC. 375 



only as are widely-spread and conspicuous ; further, that a single spe- 

 cies, and always the same individual, should be chosen, and the most 

 favourable station for observations fixed upon. 



■ 



Professor Heer agreed with the views of the first speaker, and stated 

 that in Switzerland thirty-four places had been fixed on for phsenolo- 

 gical observations, the recently completed account of which he laid be- 

 fore the meeting. He considered of great importance the records of 

 the times free of frost and snow, and of the depth of earth frozen, which 

 had been taken account of in the work lying before him. 



Dr. Cohn considered the most important object of phonological ob- 

 servations to be the fixing of the mean times of development at the 

 places of observation, for which indeed a long series of years would be 

 necessary. 



E. Ilarape perfectly agreed with his predecessor, and drew attention 

 to the fact, that in making choice of the plants to be experimented on, 

 particular attention should be paid to those whose most important 

 stages of development fall at that time of the year of which the tem- 

 perature most nearly approaches the mean annual temperature. He 

 proposed therefore, in the first place, to determine the places where 

 phaenological observations should be carried on. 



Professor Sendtner considered it advisable for the present to confine 

 the observations to those places only which now possess meteorological 

 stations, against which Professor Hofi*mann spoke. The latter w\^s of 

 opinion that the present meteorological stations are still in such a con- 

 dition as wilf not justify any comparison between climates and the pe- 

 riods of flowering plants. 



L. von Heufler requested Dr. Pritsch, who had made such observa- 

 tions the study of his life, to communicate to them his experience on 



this subject. 



After Dr. Pritsch had explaiued some of his views, he proposed that 



the whole body of gentlemen who had composed instructions for phre- 

 nological observations, should agree in the composition of one commou 

 paper of instructions, which proposal was also agreed to. 



In the first place the catalogues of Messrs. Cohn, Pritsch, and Hoff- 

 mann, of the plants which these gentlemen had recommended for ob- 

 servations, were united, and the plants were taken in alpliabetical order 

 one after another. 



The following species of plants wrrc fixed upon : 



Acer 



