268 Proceedings of Indiana Academy of Science 



at the end of the cell marked B, and under other conditions collect at 

 A. The speed, however, with which these and other movements of the 

 chloroplasts takes place is unusual. Senn* has shown that the chloro- 

 plasts of Funaria under optimal conditions of light move 4[j. in eight 

 minutes. The chloroplasts of the trichomes of Martynia, however, under 

 optimal conditions of light move much faster, in fact, namely, 21|ji, in 

 seven minutes. In the cells observed it required from 37 to 4.3 minutes 

 under fairly constant optimal light and temperature conditions for the 

 chloroplasts to traverse the cell. This shifting of the chloroplasts leads 

 to the well known change in chlorophyll color of certain plant organ.s. 



QUANTITATIVE ESTIMATION OF AERATION IN , 



LEAVES. 



F. M. Andrews, Indiana University. 



It has been known for a long time that air can be made to move 

 back and forth through the stomata of leaves and that this can be 

 accomplished in some plants with only a slight force'. Some plants 

 allow the passage of air in this way with marked ease and among them 

 may be mentioned the following: Nymphaea, Funkia, CnlUi netJnojnca, 

 Arum maculutiun, and Rumex". To these I might add Mi/rioj/ln/lhon 

 proserpinacoides which is cultivated in aquaria. 



A quantitative estimation of the amount of air which can be passed 

 through leaves has not been made. The first investigator to see air 

 pass in this way from stomata was Raffeneau Delille'. Since that time 

 Sachs' and others have worked on the problem. 



I have experimented with a number of plants in this respect. One 

 cf these was Nymphaea odorata which was an especially favorable object. 

 Air was easily caused to pass through the leaf in bubbles with a vacuum 

 of 12 mm. of mercury, which is less force than was required by the 

 specimens of the same genus mentioned by Pfeffer''. The same thing 

 was accomplished by arranging the petiole under a cylinder of water 

 filled to a height of about 30 cm. and then inverted over a dish of water 

 as indicated by Jost'. The air in this case issued from the petiole with 

 gi-eat rapidity and in large quantity. The stream of bubbles can easily 

 be made visible to a large audience by proper arrangement of a lens 

 of correct magnifying power. The volume of air thus pas.sed through 

 the leaf of Nymphaea odorata was 10 cc. in 16 seconds. One thing mu.st 

 be borne in mind with iV. odorata and that is the status of the leaf for 



* Sonn. 1. c. p. 320. 



^ Pfeffer, W. Pflanzenphysiologie Zweite Auf. 1891 Bd. 1 pp. 178-179 and literature 

 there quoted. 



- Pfeffer, W. 1. c. p. 179. 



"Raffeneau, Delille. Annales d. Scien. natur. 1841. XIV 328. Quoted by Von 

 Hohnel Jahr. f. wiss. Bot. 1S79. Bd. 12 p. 48. See othei- literature there quoted. 



^ Sachs, J. Ueber die Bewesjung der Gase in den Pflanzen. Handbuch dcr Expcrimen- 

 tal-Physiolosie des Pflanze 1865 pp. 243-262. 



^ Pfeffer, W. I. c. 



sjost, L. Lehrbuch der Botanik. 15 Auf. 1921 p. 216. 



