7 o SCIENCE PROGRESS 



annua were sealed with wax ; one was used to determine the 

 loss of water during transpiration and the other to determine 

 the condition of the stomates during the experiment. Both 

 shoots were under exactly the same conditions, and it was 

 observed that, even before the shoots were cut, the stomates 

 appeared closed ; the guard cells, however, showed a wide 

 rift above the closed pore. 



It was found that the diminution in the rate of transpira- 

 tion was 28 per cent., and that this was accompanied by a 

 diminution of 20 per cent, in the size of the rift of the stomates. 

 It is suggested, therefore, that there is a correlation between the 

 two processes. 



The investigations upon transpiration may now be con- 

 sidered. 



In the first instance, a determination 1 of the transpiration 

 of plants of Salicornia under natural conditions was carried 

 out, the plants being selected in order to obtain comparative 

 results. 



Sods were cut bearing : 



(a) Apple-green plants only. 



(b) Crimson plants only. 



(c) Mixed growths of apple-green and crimson plants. 



In the two former cases the sods were ready for experiment, 

 and in the last case the apple-green or the crimson plants 

 were removed from the different sods, pure cultures thus being 

 obtained. 



Gravimetric methods were employed ; the sods were cut to 

 fit closely into zinc boxes, and all plants except Salicornia 

 were removed. The surface of the soil was then covered with 

 a layer of cacao butter in order that evaporation from the 

 soil surface might be prevented. Weighings of the sods were 

 taken as far as possible twice a day, and the differences, due 

 to loss of water, tabulated. Readings of the wind-gauge, and 

 wet and dry bulb thermometers, also were recorded. 



At the conclusion of the experiment the plants were all 

 healthy ; they were then cut down, and the surface area in 

 each case was estimated by (1) actual measurements, or (2) 

 weighing a carefully measured moiety of plants of equal dia- 

 meter and then calculating the area of the whole. The loss 



1 This and the following observation were made by Dr. S. E. Chandler, of the 

 Imperial Institute. 



