Temperature and Growth. 
BY 
W. LAWRENCE BALLS, M.A., 
Walsingham Medal, Cambridge , 1906. 
Botanist to the Khedivial Agricultural Society , Cairo , Egypt. 
With eleven Figures in the Text. 
Introduction 
T HE object of the present paper is to analyse the effects produced 
upon the growth-process by the temperature factor. 
The research was initiated by a casual observation \ but developed into 
an attempt to determine the chemical effects of the temperature-factor by 
studying the pathological portion of the growth-temperature curve ; and 
hence to demonstrate that the time-factor is chemical in its nature, and that 
its effects can be simulated immediately. 
Isolated cells are preferable to bulky plant-bodies for such a purpose 
if the manipulative difficulties can be overcome, and I have employed 
as the subject an organism which has been under my observation for 
the past three years as a pest of the cotton crop — the so-called Sore-shin 
fungus 2 . It possesses one great advantage as a physiological subject, 
viz. the absence of any spore-formations, sexual or asexual, so that all the 
hyphae are both morphologically and physiologically equivalent. The 
chief novelty in the methods employed is the rapid rate of temperature 
change. By using so small an organism, and by recording its temperature 
with fair accuracy, it becomes possible to work through a long range of 
temperature in a short space of time. Errors due to the time-factor are 
thus minimized. 
The observations given here, and the interpretations based on them, 
do not profess to do more than attempt to follow the lines along which 
explanations may be sought of the ‘ qualitative phenomena ’ of growth. 
We are not concerned with the ‘quantitative phenomena’. Those internal 
factors, probably resident in the nucleus, which determine the rate of growth 
1 Khed. Agric. Soc. Year Book, 1905, pp. 184, 190. See also p. 33 infra. 
2 Khed. Agric. Soc. Year Book, 1905. Prel. Note, ibid., 1906. Field Notes, Preventive 
Measures. 
Annals of Botany, Vol. XXII. No. LXXXVIII. October, 1908.] 
