REVIEWS. 
521 
Bassia longifolia, Ficus Trimeni, Ficus religiosa, Meliosma Arnoctiana, 
Gyrocarpus Jacquini, Schizolobium excëlsium, and species of Bombax, 
Spondias, Cochlospermum, Terminalia, Erythrina, &c. He points out 
that different species may pass through their leafless phases during 
the wettest or the driest months. He also makes a few observations 
on the relation of the annual rings of growth to foliar periodicity. 
His observations on the transpiration of plants in Ceylon are of 
particular interest. He points out that at Peradeniya on ordinary 
days with a clear sky, evaporation commences after sunrise and 
remains feeble up to 10 A.M., but from this time it increases, until 
between 12 and 3 it reaches its maximum and then decreases until 
sunset, and subsequently dew is formed. Transpiration stops nearly 
or completely after sunset when saturation point is being approached. 
Microscopical examination of the plants convinced Holtermann that 
at Peradeniya during the moist warm period the stomata are closed 
during the night. 
At Peradeniya, from January to March there is a dry north-east 
wind, and during this period transpiration is greater than at any other 
time and may even continue all through the night. The evaporation 
on damp days, when the air is saturated, is very slight or scarcely 
perceptible. In order to emphasize the great difference between the 
transpiration during hot dry and wet days, he states that Asplénium 
Nidus on misty days lost only from O'OO to 0*21 gram of water per 
day, but on sunny days it transpired 3*50 grams. 
Holtermann worked with various plants. Cymbidium bicolor a 
common epiphytic orchid, was selected among others. This plant 
possesses thick stiff leaves (which are protected by a strong thick cuticle 
and a layer of cells running under the epidermis on the upper surface 
of the leaf) and narrow stomata. He proved that the transpira¬ 
tion from one plant of this species was, from the 23rd to the 27th 
January, both days inclusive, only 0*457 gram, or at the rate of about 
one gram in ten days. This means approximately one pound of water 
in thirteen years, a very small quantity indeed. Alstonia scholaris was 
also experimented with. The leaves of this commonly occurring tree 
are not xerophytic ; they possess normal stomata and internal tissues 
and a cuticle of average thickness. One shrub of this plant possessing 
100 leaves lost during the 13th and 14th February, when the sky was 
cloudless and the temperature high, T24 grams ; but during the 15th 
and 16th, when rain was falling, only 0*06 gram of moisture was lost 
by transpiration. 
Discussing the value of these and other observations Holtermann 
proceeds to state that there is between 12 and 2 o’clock on clear days 
in the tropics a much greater loss of water by transpiration than in 
Europe. 
There are in the tropics a large number of plants which, though 
exposed to the full rays of the sun, only lose a small quantity of 
moisture by transpiration, e.g., Euphorbia antiquorum, Cereus triquetra, 
