The Philippine Journal of Science, C. Botany. 
Vol. XIII, No. 6, November, 1918. 
ALTERNATE SHRINKAGE AND ELONGATION OF GROWING 
STEMS OF OESTRUM NOCTURNUM * 
By William H. Brown and Sam F. Trelease 
( From the Bureau of Science, Manila, P. I., and the University of the 
Philippines) 
A number of rapidly growing plants in Manila wilt during 
every comparatively dry sunny day. Conspicuous among these 
are two vines, Ipomoea nil and Thunbergia grandiflora, and a 
large shrub with pendent branches, Cestrum nocturnum. That 
these plants lose more water during the day than they absorb 
would seem to be self-evident from the fact that they wilt. 
Livingston and Brown 1 have shown that the leaves of mesophy- 
tic plants growing in Arizona contain considerably less water 
during the day than at night. Shreve 2 has shown that this 
applies not only to leaves but also to stems of Parkinsonia micro- 
phylla. The size of plant parts is apparently affected by this 
decrease in water content. Thoday 3 found that the leaves of 
many plants shrink during the day, so that they decrease in area 
two or three per cent, or in some cases as much as six per cent. 
Kraus 4 has shown that tree trunks may shrink in diameter 
during the day, while Darwin 5 6 * has found the same thing to 
be true of the fruits of Cucurbita, and Smith 8 of the fruits of 
Artocarpus. 
1 Livingston, B. E., and Brown, W. H., Relation of the daily march 
of transpiration to variations in the water content of foliage leaves, Bot. 
Gaz. 53 (1912) 309-330. 
= Shreve, E. B., The daily march of transpiration in a desert perennial, 
Carnegie Inst. Washington Publ. No. 194 (1914). 
3 Thoday, D., Experimental researches on vegetable assimilation and 
respiration. V. A critical examination of Sachs’ method for using increase 
of dry weight as a measure of carbon dioxide assimilation in leaves, Proc. 
Roy. Soc. London B, 82 (1909) 1-55. 
4 Kraus, G., Physiologisches aus den Tropen, Ann. Jard. Bot. Buitenzorg 
11 (1895) 196. 
5 Darwin, F., On the growth of the fruit of Cucurbita, Ann. Bot. 7 
(1893) 459. 
6 Smith, A. M., On the application of the theory of limiting factors to 
measurements and observations of growth in Ceylon, Ann. Roy. Bot. 
Gard. Peradeniya 3 (1906) 303. 
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