Observations on the degree of stomatal movement in certain plants * 
BurTON E. LIVINGSTON AND ARTHUR H. ESTABROOK 
The studies of Lloydt and of Livingstont on the relation of 
stomatal changes to the rate of plant transpiration have rendered 
it very desirable that some quantitative information upon the 
opening and closing of stomata in a large number of plants be 
made available. Primarily, such knowledge should hasten the 
acquisition of some generalization upon the relation between 
stomatal changes and the daily march of water loss in plants, a 
generalization that seems to be utterly lacking at the present time. 
We give, therefore, in the present paper, the results of a series 
of stomatal measurements on several different plant forms and at 
various hours of the day. Limitations in facilities and time 
prevented the testing of a larger number of forms as well as the 
undertaking of a study of the problem of stomatal influence upon 
transpiration as such; we have confined ourselves to an effort to 
determine approximately the degree of usual stomatal change 
which occurs between day and night under a somewhat widely 
representative complex of climatic conditions. The plants with 
which we have worked were all growing in the open soil in the 
recently established Botanical Garden of the Johns Hopkins 
University at Homewood, Baltimore, Maryland. The plants used 
were Funkia ovata, Isatis tinctoria, Allium Cepa, Eichhornia speciosa, 
and Oenothera biennts. 
Following Lloyd’s method,§ at various times of day and night 
samples of epidermis were stripped from the leaves without re- 
moval of the latter from the plants, and were quickly placed in 
absolute alcohol contained in suitable vials. Different but similar 
leaves of the same plant were used for any single series of observa- 
tions. Ata later time the samples were mounted in a solution of 
* Botanical contribution from The Johns Hopkins University No. 27. 
+ Lloyd, F. E. The physiology of stomata. Pub bl. 89 Carnegie Inst. 1908. 
t Livingston, B. E. Stomata and transpiration in Tradescantia zebrina. Science 
IT. 29: 260, me 1909. 
§ Loc. cit. p. 26. 
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