1902.] Influence of an Excess of Carbon Dioxide on Plants. 413 



Plate 8. — Solanum atropurpureum. 



Under experiment for 28 days. 



A. Plants grown in ordinary air. 



B. „ in air containing 11*4 parts of C0 2 per 10,000. 

 Plate 9. — Fuchsia. Dark -leaved variety. 



Under experiment for 28 days. 



A. Plants grown in ordinary air. 



B. „ in air containing 11 '4 parts of CO2 per 10,000. 

 Plate 10. — Fuchsia. Dark-leaved variety. 



Under experiment for 54 days. 



A. A plant grown in ordinary air. 



B. „ in air containing 1 1 *4 parts of C0 2 per 10,000. 



N.B. — The scale on the rod is in inches. 



" On the Influence of an Excess of Carbon Dioxide in the Air on 

 the Form and Internal Structure of Plants." By J. Bretland 

 Farmer, D.Sc, F.E.S., Professor of Botany in the Eoyal 

 College of Science, London, and S. E. Chandler, A.K.C.S. 

 Eeceived May 6,— Eead May 29, 1902. 



The plants which form the subject of the present enquiry were 

 kindly handed over to us by Messrs. Horace Brown and F. Escombe. 

 They were preserved in alcohol, and had previously served as the 

 material on which the researches of these investigators on the influence 

 of varying amounts of carbon dioxide in the air on the photosynthetic 

 processes of leaves and on the mode of growth of plants* had been 

 conducted. 



The series, consisting of the following five plants, viz., Kalanchoc 

 Welwitschii, Solanum atropurpureum, Begonia gracilis, Irnpatiens platypetala, 

 Fuchsia, sp., included in every case specimens which had been grown in 

 a greenhouse in ordinary air containing 3*29 parts of carbon dioxide 

 in 10,000 volumes of air, and others that had been cultivated under 

 conditions as similar as possible except that the atmosphere contained 

 about 3*5 times (11*47 per 10,000) the amount of carbon dioxide nor- 

 mally present in ordinary air. For the sake of brevity we shall refer 

 to them as the air or control and as the C0 2 plants respectively. 



We directed our attention more especially to the following 

 points : — 



(1.) The relative dimensions of the inter nodes. 



* Cf, H. Brown and F. Escombe, " On the Influence of Varying Amounts of 

 Carbon Dioxide in the Air on the Photosynthetic Processes of Leaves and on the 

 Mode of Growth of Plants," 'Eoy. Soc. Proc.,' vol. 70, in which full details are 

 given as to the methods of experiment and the external appearances presented by 

 the plants. 



