BOTANY. 849 



species of monocotyledonous and dicotyledonous plants, and its localization and 

 methods of solution and use arc discussed. A brief bibliography is given. 



The action of formaldehyde on the respiration of plants, A. Benedicenti 

 and G. B. de Tom (Atti. li. Inst. Venelo Sci., Let. et Art., 61 {1901-2), No. 2, pp. 

 829-850; abs. in Bot. CerUbl, 96 {H>04), No. 43, pp. $27, $28)— The different theories 

 regarding the formation of formaldehyde in plants as a process in carbon dioxid 

 assimilation are reviewed. The authors do not accept the theory that formaldehyde 

 is a definite product of the plant, but show that it is highly injurious to plant life. 

 If formed at all in the plant it must be immediately condensed into some form of 

 carbohydrate or other substance rich in carbon. 



To test the effect of formaldehyde on plants a large number were grown under 

 sharply controlled conditions, in which formaldehyde was added to the atmosphere 

 and the carbon dioxid evolution accurately determined. At first the amount of car- 

 lion dioxiil evolved was greatly increased, the formaldehyde seeming to have a 

 stimulating effect on the plants, but later there was a marked diminution, and the 

 total carbon dioxid given off was less than that liberated by plants growing in normal 

 atmospheres. If continued for a sufficiently long time the plants were invariably 

 killed. 



The duration of the stimulus and the death of the plant were in almost direct pro- 

 portion to the amount of formaldehyde present. The periods of normal fluctuation 

 in the respirative activity of the plants were not affected except when the amount of 

 formaldehyde was excessive. 



The physics and physiology of protoplasmic streaming in plants, A. .1. 

 Ewart {Oxford: Clarendon Press, 190.], pp. 131; abs. in Hot. Centbl., 90 {1904), No. 41;, 

 j>/>. 502, 508). — The author shows that the velocity of streaming is largely dependent 

 upon the viscosity of the protoplasm, and hence upon the percentage of water present. 

 Within certain limits, as the temperarure rises the viscosity decreases, increasing the 

 velocity of streaming. 



The energy expended in protoplasmic streaming is a very small fraction of that 

 produced by respiration. The force required increases enormously as the diameter 

 of the passage decreases, so that the transference of masses of highly viscous proto- 

 plasm becomes practically impossible except in the case of relatively large connecting 

 strands of sieve plates. The energy for streaming can be derived either from aerobic 

 or anaerobic respiration. 



Strong light retards streaming, while weak light may indirectly accelerate it in 

 chlorophyll-bearing cells. Acids, alkalis, ami metallic poisons retard, while dilute 

 alcohols and anesthetics accelerate streaming, but when concentrated they always 

 retard it. Electric currents, when not too strong, were found to accelerate proto- 

 plasmic streaming. 



Investigations on the acidity of plants, E. Charabot and A. Hebert (Compt. 

 Rend. Am, I. Sri. [Paris], 188 (1904), No. 26, pp. 17 14-17 W)-— Studies are reported 

 on the acidity of plants, particular attention being paid to the volatile acids in such 

 plants as peppermint, geranium, sweet basil, bitter orange, etc. 



In the cast- of peppermint, the maximum of free volatile acids was constantly 

 highest in the leaves. The amount of volatile acids was found to vary at different 

 times, decreasing at the time of the appearance of the inflorescence, increasing with 

 the expansion of the flowers, and diminishing to a minimum at a later stage. It was 

 found that plants grown constantly in the shade showed a higher acidity in the root 

 than in the leaves. The suppression of the inflorescence increased the volatile acids 

 in the leaves, to the detriment of other organs of the plants. 



The authors have also determined the alkalinity of the ash of the different plants, 

 which it was found reached a maximum in the ash of the leaves. In the case of 

 plants grown in the shade the proportion of combined organic acids increases, and at 



