76 Knight . — Use of the Porometer in Stomatal Investigation . 
should be attached to more than one leaf, but for reasons already stated the 
chambers should be about the same size. 
It is with great pleasure that I record my indebtedness to Professor 
V. H. Blackman, at whose suggestion this work was undertaken, and under 
whose guidance it has been carried out. 
Department of Plant Physiology and Pathology, 
Imperial College of Science and Technology. 
References cited. 
1 . Darwin, F. : Observations on Stomata. Phil. Trans., 190, B., 1898, p. 531. 
2 . Stahl: Einige Versuche iiber Transpiration und Assimilation. Bot. Zeitung, 1894, p. I1 7 * 
3 . Lloyd, F. E. : Leaf-water and Stomatal Movement in Gossypiiun , and a Method of direct 
Visual Observation of Stomata in situ . Bull. Torr. Bot. Club, 40, 1913, p. 1. 
4 . Lloyd, F. E. : The Physiology of Stomata. Carnegie Institute Publications, No. 89, 1908. 
5 . Darwin, F., and Pertz, D. F. M. : New Method of estimating the Aperture of Stomata. 
Proc. Roy. Soc., 84, B., 1911, p. 149. 
6. Knight, R. C. : A Convenient Modification of the Porometer. New Phytologist, vol. 14, 1915, 
p. 212. 
7 . Balls, W. L. : The Stomatograph. Proc. Roy. Soc., 85, B., 1912, p. 40. 
