RESPIRATION OF PLANTS. 



647 



meters of both apparatuses, previously compared, must be frequently read off in order to 

 detect the variations of temperature. If the bulbs are small enough, the elevation of 

 temperature in the funnel may be observed even with single flowers. In order to reduce 

 still further the amount of evaporation and 

 radiation, it is convenient, before the bell- 

 glass g is placed over, to cover the funnel 

 with a perforated glass plate, the thermo- 

 meter being inserted through its perfo- 

 ration. 



It is possible under favourable circum- 

 stances to observe by means of this con- 

 trivance a rise of temperature of 1*5° G. 

 with 100 or 200 peas, while the roots are 

 developing ; the anthers of a flower of the 

 gourd caused a rise of about o'S'' C. in 

 a tolerably large thermometer with the 

 bulb of which they were in contact on 

 only one side. A single capitulum of Ono- 

 f or don Acanthium produced an elevation of 

 o'72°C; the stamens of a single flower of 

 Nymphooa stellata one of about o'6° C. A 

 number of flower-buds of Anthemis chryso- 

 lenca heaped round the thermometer rose 

 as they unfolded about i'6° C. 



It will be readily understood that 

 flowers must not be used for these experi- 

 ments as soon as they have been gathered ; p^- 

 but that it is necessary to wait for some 

 hours till they have acquired the temperature of the room 

 given elsewhere.) 



ApparaiiLs for observing' the rise of temperature 

 in flowers and germinating seeds. 



(Further details will be 



CHAPTER III. 

 GENERAL CONDITIONS OE PLANT^LIEE. 



Sect. 8. The Influence of Temperature on Vegetation^ can only be 

 investigated scientifically by observing the influence of definite and different degrees 

 of temperature on the separate vital phenomena of plants, i.e. on the various pro- 

 cesses of assimilation and metastasis, of diffusion, growth, the variations in the 

 turgidity of the cells and tension of the tissues, on the movements of protoplasm 

 and irritable organs and of those endowed with periodic motion, &c. 



The determination of the facts which have here to be investigated depends on 

 an accurate knowledge of the temperature of the plant in any given case, or rather 

 on that of the part of the plant in question on which the experiment is to be made. 



For more detailed proofs see my Handbook of Experimental rhysiology, p. 48 et seq. 



