CHAPTER VII. 



TEMPERATURE. 



OF the several conditions upon which depends the 

 geological distribution of plants that which is most 

 easily recognised, and most generally observed, is tem- 

 perature. There are hardy arborescents, such as the 

 gooseberry, the currant, and the cherry, which never fruit 

 in warm countries ; and there are tropical and sub-tropical 

 fruit trees such as the bread-fruit, the love apple, the 

 banana, and the grape, which may fruit with us in a hot- 

 house, but not in the open air. During the meeting of 

 the British Association in Aberdeen, in 1859, at which time 

 I held the Chair of Botany in King's College, I was visited 

 by a Polish savant, Professor Bialoblotsky, who was desirous 

 of particular information in regard to the temperature of 

 the district. Having stated generally his enquiry, he 

 said: 'I have observed indications of the prevailing 

 temperature. I see the furze flourishes luxuriantly ; and 

 I know of course that the cold is by no means severe. I 

 have also remarked that the walnut grows well, but does 

 not fruit ; and I know thus something of the limit of 

 heat in summer both as to degree and duration. But 

 there are several details in regard to the duration of 

 intermediate temperatures, and of the maxima and minima 

 of which I wish to be informed, and also details of con- 

 ditions under which they occur/ 



So may one learn elsewhere much in regard to tempera- 

 ture from observation of the vegetation. 



The following statements by Schleiden, formerly Pro- 

 fessor of Botany at Jena, and afterwards at Dorpat, taken 



