298 PHYSIOLOGY [Box. Absts., Vol. X, 



silver-reducing power at the moment of the chloroplast's death, and (3) that the substance 

 in question is identical with the carbon dioxide-reducing substance or has a close relation 

 with carbon dioxide assimilation. The reaction in question suggested to the author the 

 reduction of silver nitrate in the cold by pyrocatechol. This substance is precipitated by 

 neutral lead acetate, and the lead salt thus produced, even when washed until no free pyro- 

 catechol is present, gives a distinct reduction of silver. Sections of various leaves treated 

 with lead acetate solution and then washed free of excess of the lead salt showed ability to 

 reduce silver nitrate as in living cells, — evidence that a "Lebensreaktion" is not involved. 

 Czapek inactivated the ferments present and extracted a substance which gave strong silver 

 reduction in the cold. The chemical investigation has not been completed but the substance 

 has been secured in crystalline form. It seems unlikely that it has anj^ connection wdth car- 

 bon dioxide assimilation. The quantity of the silver-reducing substance in the leaves was 

 quickly reduced by enzyme action, on drying, when no measures were taken to inactivate the 

 enzymes. — R. M. Holman. 



1934. DuTCHER, R. A., H. M. Harshaw, and J. S. Hall. Vitamine studies. VIII. The 

 effect of heat and oxidation upon the antiscorbutic vitamine. Jour. Biol. Chem. 47: 483-488. 

 1921. — The substance or substances (vitamin) responsible for the antiscorbutic properties 

 in orange juice are susceptible of oxidation, but in the absence of oxidizing agents are stable 

 to heat up to the boiling point of orange juice. — G. B. Rigg. 



1935. Eddt, W. H., Hattie R. Heft, Helen C. Stevenson, and Ruth Johnson. Stud- 

 ies in the vitamine content. II. The yeast test as a measure of vitamine B. Jour. Biol. Chem. 

 47: 249-275. 1921. — Until a basal mediimi is worked out that provides an optimimi of all 

 the factors, except vitamin B, the test must be considered of little value in the estimation 

 of true vitamin content. — G, B. Rigg. 



1936. Everest, A. E., and A. J. Hall. Anthocyanins and anthocyanidins. Part IV. 

 Observations on: (a) Anthocyan colors in flowers and (b) the formation of anthocyans in plants. 

 Proc. Roy. Soc. London B, 92: 150-162. 1921.— The author confirms the hypothesis of Will- 

 statter et al. on the constitution of the blue anthocyan pigments. The findings of K. and Y. 

 Shibata and Kasiwagi (Jour. Amer. Chem. Soc. 41 : 208-220. 1919) are considered of no value. 

 The blue colors in anthocyan flowers are considered as due to anthocyan phenolates of alkali 

 or alkaline earth metals or complex anthocyan iron salts. In the former case the pigments 

 decolorize on standing, due to a pseudo-base formation. The effects of various salts on 

 anthocyan pigments are recorded and the preparation of the mother substance is noted. 

 Evidence is adduced from a study of developing buds to show that flavonol formation pre- 

 cedes anthocyanin production, probably as an intermediate step. No observational evi- 

 dence is given for the production of flavonols through anthocyanins. — Paul B. Sears. 



1937. Howard, Grace E. Extraction and separation of the pigments of Nereocystis 

 luetkeana. Publ. Puget Sound Biol. Sta. 3 : 79-91 . 1921 . — It is possible to extract chlorophyll 

 a and b, carotin, xanthophyll, and fucoxanthin, following the general processes used by 

 Willstatter, but it seems impossible to do this with pure solvents. When put into a colloidal 

 state the chlorophyll carries a negative charge. Magnesium proved to be present in chloro- 

 phyll; and there is good evidence of the presence of chlorophyllase in kelp. — T. C. Frye. 



1938. Kohn-Abrest, fiiviiL. Detecting poisons in food substances. Sci. Amer. Monthly 

 3: 325-328. 1921, [Translated from La Science et La Vie Dec, 1920; Jan., 1921.]— There is 

 discussed, among other things, the occurrence of hydrocyanic acid in beans and stone fruits. — 

 Chas. H. Otis. 



1939. Kraemer, Henry. Plant colors. Amer. Jour. Pharm. 93: 414— il6. 1921, — In 

 this review of the known facts concerning the nature of plant color, the author discusses the 

 anthocyanins. The name anthocyanin, as 1st given by Marquardt, may be used to designate 

 all plant colors other than green and yellow, which are plastid pigments. — Anton Hogstad, Jr. 



