222 EXPERIMENT STATION EECORD. 



and fibrous systems are little developed, and tlie medullary lacunae are smaller 

 and thicker walled than in wet seasons. 



Recent studies on respiration in tropical plants and on coloration of 

 organs, F. Tobleb {Natmnvlssenschaftcn, 2 {1914), No. 9, p. 215). — Noting re- 

 cent results of investigations as reported by Kuyper, Plester, and Hill, jr. 

 (E. S. R., 26, p. 822; 28, p. 728; 29, p. 538), the author holds that while a direct 

 parallel between respiration rate and chlorophyll content has not been estab- 

 lished, a relation doubtless exists between respiration and assimilation. 



A method of studying transpiration, F. Daewin {Proc. Roy. Soc. [London], 

 Ser. B, 81 (1914), No. B 595, pp. 269-280, figs. 9).— The author describes and 

 gives an account of experiments on transpiration, the investigation being 

 conducted with leaves of the cherry laurel, the stomata of which had been 

 blocked by a coating of cacao butter or vaseline and communication with the 

 intercellular spaces of the leaves taking place through incisions made in the 

 leaves. The rate of transpiration was estimated by a potometer. 



The relation between transpiration and humidity in a number of experiments 

 is shown by curves which indicate that transpiration for different degrees of 

 relative humidity is roughly in a straight line. From this it is inferred that 

 a definite relation exists between transpiration and relative humidity. Another 

 characteristic brought out by the curves is the fact that transpiration in satu- 

 rated air is not zero. 



The effect of light on the transpiration of leaves, F. Daewin (Proc. Roy. 

 Soc. [London], Ser. B, 87 (1914), No. B 595, pp. 2Si-299). -^Employing tlie 

 method described above, the author has studied transpiration in leaves and 

 shoots of cherry laurel and ivy. The results of the studies are tabulated. 



It appears that a remarkable degree of variability was observed between 

 transpiration in light and darkness. On certain dates there was no difference, 

 while at other times the transpiration in light was double that taking place 

 in darkness. The average rate of transpiration in light and darkness in the 

 ivy was 136 to 100 and in the laurel 132 to 100. Discussing the reason for 

 increased transpiration in light, the author says it may be due either to the 

 fact that the chloroplasts are warmed by the absorption of radiant energy, or 

 that light produces an increased permeability of the plasmic membrane to 

 water. 



The influence of light and temperature changes on the germination of 

 Chloris ciliata, G. Gassner (Jahrh. Hamburg. Wiss. Anst., 29 (1911), Beiheft 

 S, pp. 1-121, figs. 3). — This article gives in greater detail substantially the same 

 statement of results as does a contribution already noted (E. S. R., 27, p. 219). 



The action of light on chlorophyll, H. Wager (Proc. Roy. Soc. [London], 

 Ser. B, 81 (1914), No. B 596, pp. 386-401) .—An account is given in this paper 

 of some of the effects produced by light on chlorophyll. 



When chlorophyll is exposed to light at least two substances are formed, one 

 of which is an aldehyde and the other an active chemical agent capable of 

 liberating iodin from potassium iodid. The author claims that, so far as ex- 

 periments on dead chlorophyll extracts can be taken as an indication, the alde- 

 hyde produced is a product of the photodecomposition or photo-oxidation of 

 chlorophyll, and is not a result of the direct photosynthesis of carbon dioxid 

 and water, as claimed by Usher and Priestley (E. S. R., 25, p. 634). 



Formaldehyde as an oxidation product of chlorophyll extracts, C. H. 

 Warner (Proc. Roy. Soc. [London], Ser. B, 81 (1914), No. B 596, pp. 318-385).— 

 A study was made of chlorophyll obtained from grass by extraction with 

 alcohol, the extract being exposed to electric light and sunlight in glass jars. 



Where the film of chlorophyll was in contact with air containing carbon 

 dioxid and water vapor, the development of formaldehyde is said to be due to 



