Notes. 
59i 
Meconopsis cambrica . ioo°C. 
Schizopetalon Walker i . 105° 
Brassica Rapa . . 1 1 o° 
Eschscholtzia californica 1 1 o° 
Laduca sativa . . 114 0 
Helianthus argophyllus no° 
Lolium perenne . . no° 
Helianthus annuus 
112° C. 
Pisum sativum 
112° 
Trigonella Fenumgraecum 
90° 
Lotus tetragonolobus 
I IO° 
Convolvulus tricolor 
120° 
Nicotiana Tabacum 
112° 
Galtonia candicans 
105 ° 
Seeds of Lagenaria vulgaris and Heradeum giganteum were unable 
to germinate after exposure to a temperature of 90° C. 
The seeds of any one species show considerable individual 
differences in their power of resisting high temperatures. Thus a 
large percentage of a sample of seeds, say of Avena sativa , will ger- 
minate after exposure to a temperature of ioo°-io5° C., while only 
a very small percentage will germinate if exposed to n8°C. 
The time needed for germination is increased by exposure to 
temperatures near the maximum. In a general way the higher the 
temperature to which the seeds are exposed the longer will be the 
period of germination. 
Long exposure to a comparatively low temperature may prove 
more fatal than a short exposure to a high temperature. Thus seeds 
which will germinate successfully after one hours exposure to 
1 1 o°— 1 20° C. will not germinate after twelve days’ exposure to a 
temperature of 95°-97° C. 
HENRY H. DIXON. 
Trinity College, 
Dublin. 
THE EFFECT OF TEMPERATURE ON CARBON DIOXIDE 
ASSIMILATION \ — This investigation differs from any which have 
preceded it on the same subject in the attention paid to uniformity 
in the environment of the leaves before the experiment. Recent work 
has shown that both the assimilation and the respiration of a leaf 
depend on its previous nutrition and temperature. For this reason 
a separate leaf was used for each temperature, care being taken to 
keep them for some time under exactly similar conditions. 
Leaves of the Cherry Laurel ( Prunus Laurocerasus ) were employed 
throughout. 
1 Abstract of paper read before Section K of the British Association, Belfast, 
1902. 
