AGRICULTURAL fiOTANY. 29 



that if liberation of Leat is tlie essential result of respiration, respiration must 

 be an excessively wasteful process. He does not believe that respiration is 

 priniurily carried on for the purpose of furnishing the living organism with 

 energy in the form of heat, as is often taught. lie states that " the liberation 

 of heat ma5' be used, like carbon dioxid, by the physiologist as a gauge of the 

 activity of respiration, but like carbon dioxid, it must be regarded by him as 

 an end product, a waste, and not the essential product. The essential product 

 of respiration may be energj', but if so, it is that energy which is immediately 

 convertible, and is converted into work by the organism. On the other hand, 

 respiration may be essentially a process of purification, in which useless or 

 injurious substances are converted into forms which can be eliniinateil." 



In conclusion he says: "In this study of heat liberation, therefore, I believe 

 I have been occupied with an unessential, although inevitable, feature of the 

 process of respiration. The essential part of the process of respirntion is much 

 more likely to be found to be chemical and hot physical." 



Incipient drying- in plants, B. E. Livingston (Alis. in Science, n. ser., 

 35 (1012), xA'o. 897, jyp. 3D.',, 3fl5).— Attention is called to the fact that when 

 water loss from the exposed niembranes of leaves occurs at a higher rate than 

 that at which water of imbibition enters these membranes the surfaces begin 

 to dry. This phenomenon, which the author terms incipient drying, is said to 

 occur in leaves which are subjected to relatively high transpiration. The 

 drying acts as an automatic clKick upon transpiration. 



The water balance of desert plants, I). T. M.vcDougal (Ann. Dot. [London'\, 

 26 (1912), No. 101, pp. 71-93, pla. 5). — In continuation of previous accounts 

 (E. S. li., 2G, p. 530), the author describes experiments with Echinocactus, 

 Carnegiea, Opuntia, Ibervillea, Dioscorea, Drodij^a, and other jilants and dis- 

 cusses the i)hysiological value of the water balances of the plants studied. 



He states that the actual physiological value of water balances varies widely, 

 as shown by his experiments with the different plants. All showed a high rate 

 of water loss inunediately upon removal from the soil, after which the curve of 

 tran.spiration fell. In some instances the jilants remained alive for a number 

 of years. 



The relation of soil acidity to plant societies, A. W. Sampson (Ah ft. in 

 Science, n. ser., 35 (1912), No. 89S, p. 1,36). — This is an abstract of a paper pre- 

 sented before the Botanical Society of Washington in February, 1912, which 

 reports a study on the relation of soil acidity to plant cover based on range 

 vegetation observations made in the Wallowa Mountains of northeastern 

 Oregon. 



It is stated that " the Leguminosje are commonly extremely sensitive to acid 

 soils, while many ericaceous species are rather closely confined to acid soils. 

 For example, Trifoliiim repens fails in soils requiring for neutralization the 

 relatively small amount, locally, of 5.000 lbs. of lime per acre-foot, while no 

 species of Vaccinium is known that can be grown successfully in neutral or 

 alkaline soils. Again, some genera (e. g., Populus and Rosa) are apparently 

 indifferent as regards soil preferences. The preeminent forage plant of the 

 Wallowa iMouutains, Fcstitca viridula, varies very widely in adaptability to 

 acidity. The soils on which it grows luxuriantly vary in lime requirements 

 from 5,000 to 41,000 lbs. per acre-foot. The 4 species of Poa and the 2 species 

 of Agropyron occurring locally reach their best development on calcareous and 

 neutral soils." 



The weeds of arable land in relation to the soils on which they grow, II, 

 Winifred E. Brenchley (A7vi. Bat. [London']. 26 (1912), No. 101, pp. 95-109).— 

 A study of 106 species of weeds to determine whether definite associations exist 



