RESPIRATION 193 



The succulent plants in the first series, it will be noted, respire on an average 

 far less actively than the others. 



As examples of excessive respiratory activity, GARREAU'S (1851) data, 

 obtained from germinating seeds, may be next quoted : 



Plant Temoerature Fresh wei g ht Dr y weight CO 2 in CO 2 per t gr. 



of seeds. of seeds. 24 hrs. of dry weight. 



Lactuca sativa 16 C. 4.5 gr. 0-40 gr. 33 ccm. 82.5 ccm. 



Valerianella olitoria 4.0 0-20 25 125 



Papaver somniferum 5-8 ,, 0-45 55 122 



Sinapis nigra 8.5 0.55 32 58 



Lepidium sativum 2.5 0-25 12 48 



The same investigator gives the following values for buds : 



Plant. 



Syringa 



Sambucus nigra 

 Ribes nigrum 

 Tilia europea 



These numbers cannot be directly compared with those obtained by SAUS- 

 SURE (1804) (compare SACHS, 1865, p. 277) for flowers and floral organs, be- 

 cause that author estimated the volumes of oxygen absorbed and reckoned the 

 volume of the organ in question as unity. Has results are, all the same, of great 

 interest because he investigated not only the flowers but also the leaves of the 

 same plants in darkness. 



Oxveen used uo bv Ox y en used U P b y the Oxygen used up by 



Plant ' flowers "n 24 hrs y reproductive organs the foliage leaves 



in 24 hrs. in 24 hrs. 



Cheiranthus cheiri no 18-0 4-0 



Polyanthus tuberosus 9.0 3-0 



Tropaeolum majus 8-5 16.3 8-3 



Passiflora serratifolia 18.5 5.25 



Cucurbitamelopepod 7.6 n 7 (anthers) 



Cucurbita melopepoo 3.5 4 7 (stigmas) 



Ilex aquifolium 0.86 



Viburnum tinus 2-23 



Juglans regia 4.4 



Populus alba 46 



Finally, a few examples may be quoted by way of demonstrating the 

 variations which occur during development, and the first of these is of interest 

 as giving the absolute amount of respiration. The inflorescence of Arum used 

 up the following amounts of oxygen (in ccm.) in successive hours (GARREAU, 

 1851) : 



ist hour 

 2nd 

 3rd 

 4th 

 5th 



In 18 following hours 

 JOST 



