210 PHYSIOLOGY [Bot. Absts., Vol. IV, 



parative results. However, a light intensity which can darken Bunsen's silver chloride paper 

 to the standard color in 1 second is taken as 100. For Sinapis the CO2 intake is 6 mgm. CO2 

 per 50 sq. cm. per hour at 20 C C, respiration 0.8 mgm. C0 2 per50 c. cm. per hour at 20°C. In 

 4 weeks there was an increase in the dry weight from 0.5 grams to 38 grams for 100 plants. — 

 For Oxalis the C0 2 intake is only 0.8 mgm. per 50 sq. cm. per hour at 20°C, while the res- 

 piration is 0.1 to 0.2 mgm. C0 2 per 50 c. cm. per hour. The daily per cent increase in dry 

 inntter is 2.1 per cent. — .4. L. Bakke. 



1429. Buder, J. Zur Biologie des Bakteriopurpurins und der Purpurbakterien. [Contri- 

 bution to the biology of the purple bacteria and their pigment.] Jahrb. Wiss. Bot. 58: 525-628. 

 /'/. 5, fig. 1-5. 1919. — The paper contains a critical historical consideration of the purple bac- 

 teria, the groups of purple organisms, the pigments and their relation to the spectrum, and 

 the connection between absorption and the physiological action of light rays of different wave 

 lengths. The author's own researches were concerned mainly with the effect of light rays of 

 different wave lengths on the movement of the bacteria, The fact that the pigments of the 

 purple bacteria absorb the infra red, the yellow, and the green rays, that is, those regions of 

 t lie spectrum which are not absorbed by the chlorophyl, enables these organisms to live in 

 water underneath thick layers of vegetation. However, the bacteria grow as well or better 

 in the open water where they may occur at greater depths than when shaded by vegetation. 

 In conclusion, the author discusses the theories of Engelmann and Stahl in relation to the im- 

 portance of the yellow pigments in assimilation. Although Iwanowski and Willstatter have 

 denied any connection between the presence of these pigments and assimilation, the author 

 seems to think that Stahl's theory still stands. The researches have shown that the selective 

 absorption of the chromatophores of the purple bacteria is an established fact and of the great- 

 est importance to the organisms. — E. F. Artschwager. 



1430. Crocker, William. Photosynthesis. [Rev. of: Osterhout, W. J. V., and A. R. 

 C. Haas. Dynamical aspects of photosynthesis. Proc. Nation. Acad. Sci. 4: 85-91. 1918.] 

 Bot, Gaz. 67: 182. 1919. 



1431. Ewart, Alfred J. On chlorophyll, carotin and xanthophyll, and on the produc- 

 tion of sugar from formaldehyde. Proc. Roy. Soc. Victoria (N. S.) 30: 178-209. 1918. [Re- 

 ceived 1919.1 — Chlorophyll acts as a light-energizing enzyme in the assimilation of C0 2 . It 

 lakes a direct part in the chemical changes which result in the formation of carotin, xantho- 

 phyll, phytyl, and glaucophyllins as intermediate products and of glucose, levulose, formalde- 

 hyde and oxygen as end products. There is a continual reconstruction of the chlorophyll 

 molecule during which a large part of the energy represented by the carbohydrate products 

 is absorbed. Carotin, besides being protective, seems to be especially important in providing 

 the massive hydrocarbon combination in the phytyl radicle of chlorophyll which is necessary 

 to convert the dicarboxylic glaucophyllin into the tricarboxylic chlorophyll. Xanthophyll 

 was reduced to carotin by metalic reductases but no oxidase was found which would convert 

 carotin into xanthophyll. A method is described for rapidly polymerizing formaldehyde 

 to sugar; calcium and sodium tartrates w r ere obtained as by-products. Equations are given 

 to show how chlorophyll could act as a photic or lytase enzyme to convert CO a and H 2 into 

 carbohydrates. — E. T. Bartholomew. 



1432. Osterhout, W. J. V. Apparatus for the study of photosynthesis and respiration. 

 Bot. Gaz. 68: 60-62. 1 fig. July, 1919. — The photosynthesis and respiration of land plants 

 may be studied by placing them in a chamber in which the gas can be made to bubble through 

 an indicator. The changes in the color of the indicator indicate the changes in the tension 

 of C0 2 . The method is reported serviceable for classroom demonstration as well as for 

 investigation. — W. J. V. Osterhout. 



1433. Schroder, H. Der Chemismus der Kohlensaureassimilation im Lichte neuer 

 Arbeiten. [The chemistry of photosynthesis in the light of new researches.] Ber. Deutsch. 

 l'>ot. (Ics. 36: 9-27. 1919. — This paper is an attempt at a critical review of the modern con- 



