Some Experiments on the Influence of Temperature 
on the Rate of Growth in Pisum sativum. 
BY 
I. LEITCH, B.Sc. 
With Plate I and ten Figures in the Text. 
T HE first work of importance on the subject of the relation of tempera- 
ture to growth-processes in higher plants is that of Sachs (’60), on the 
effect of temperature on germination. His method is to compare the 
amounts of growth in a given time at different temperatures. The time 
is measured from the end of the soaking, and in Pisum the time- interval 
chosen is forty-eight hours. F or Pisum he concludes that the temperature 
at which germination proceeds most quickly is below 22 °. This method 
seems to be defective, since the amount of growth of the roots in the rather 
long period of forty-eight hours will be much affected by the ease or difficulty 
with which the root bursts the seed-coat, there being great differences in this 
respect between peas treated in exactly the same manner and giving the 
same growth-curve afterwards. 
Koppen (’70) finds that alterations of temperature exercise a retarding 
influence on growth, and makes a number of determinations of the rates 
of growth at temperatures, for Pisum , from io° to 40 °. These values show 
a great inconstancy, and besides, in view of the experimentation-time 
of forty-eight hours and the method employed, their value is small. 
Petersen (’74) points out the obvious defects of Koppen’s work, demon- 
strates that variations in temperature, as such, have no effect upon growth, 
and that the curve of growth at non-injurious temperatures must be a curve 
convex to the temperature-axis. 
Sachs (’87) investigates the occurrence of the Grand Period in different 
seedlings, and finds it to occur in Pisum on the ninth or tenth day. It is 
to be noted that in his experiments on the fifth to sixth day, the tempera- 
ture varies between io° and 19 - 8 °, a variation sufficient to disturb the result 
considerably. He gives figures for the relation of growth to temperature in 
Zea Mais, and quotes a judicious selection from Koppen’s figures showing 
a relation agreeing in type with his own determinations. 
[Annals of Botany, Vol. XXX. No. CXVII. January, 19x6.] 
