378 



SCIENCE 



[N. S. Vol. XXXVII. No. 949 



that prairie fires especially could not have been 



the cause. 



Vegetation Features of the Columbus Quadrangle: 



A. Dachnowski and F. B. H. Beown. 

 TJw Genus Helianthus in Southern Michigan: S. 

 Alexander. 



This paper involves the recognition of a large 

 number of new forms. An attempt is made to 

 classify sunflowers on the basis of their under- 

 ground systems and of their venation. 

 The Regulatory Formation of Tannase in Asper- 

 gillus niger and Penicillium sp.: Lewis Knud- 

 soN, Cornell University. 



Aspergillus niger, Penicillium rugulosum and 

 Penicillium sp., can ferment tannic (gallo- 

 tannic) acid, gallic acid resulting. Employing 

 the two organisms Aspergillus niger and Penicil- 

 lium sp., the writer made experiments in which a 

 modified Czapek's solution was employed as the 

 nutrient medium. When the source of carbon is 

 tannic acid, gallic acid or cane sugar supple- 

 mented by tannic or gallic acids at certain con- 

 centrations, these organisms form the enzyme tan- 

 nase. In the absence of tannic or gallic acids no 

 tannase is formed. In these experiments the efEect 

 of each of fourteen other organic compounds was 

 tested, but none could stimulate the formation of 

 the tannase. The gallic acid is not as efficient as 

 the tannic acid in stimulating to formation by 

 these organisms the enzyme tannase. 



In certain experiments the influence of concen- 

 tration of tannic acid on the quantity of the tan- 

 nase produced was determined. The source of 

 carbon was 10 per cent, sugar supplemented by 

 tannic acid in variable quantities. It was found 

 that the greater the concentration of tannic acid 

 present the greater is the quantity of the enzyme 

 tannase produced. The greatest quantity of en- 

 zyme is produced when tannic acid is the sole 

 source of carbon. In other experiments the source 

 of carbon was 2 per cent, tannic acid, and variable 

 quantities of cane sugar employed. It was found 

 that the higher the concentration of cane sugar 

 the less is the quantity of tannase produced. 

 The Relation of Ventilation to the Mespiration of 

 Fruits: George E. Hill, Jr., Missouri Botanical 

 Garden. 



A study was made of the respiration and other 

 metabolic phenomena of green and well-ripened 

 fruits which had been placed in nitrogen, hydrogen 

 air and carbon dioxide. Cherries, blackberries, 

 green, market-ripe and very ripe peaches, ripe red 

 Astrachan apples and Concord and Catawba 



grapes were used. Particular attention was given 

 to an investigation of the common cold storage 

 injury to peaches, "ice-scald," and the results 

 point quite definitely to a close relationship be- 

 tween it and anaerobic respiration. The keeping 

 qualities of the fruits in storage in the gases 

 named, and the relation of these to ventilation, was 

 also considered. The experiments were run in 

 triplicate and the temperature was kept constant 

 by an apparatus devised especially for the pur- 

 pose. 



Conditions Affecting the Development of Lycopin 

 in the Tomato: B. M. Duggar, Missouri Botan- 

 ical Garden. 



Willstiitter and Eseher have shown that the red 

 pigment of the tomato (lycopin, solanorubin) and 

 carotin (derived from the carrot) are isomeric com- 

 pounds, readily distinguishable by their physical 

 properties. In the ripening tomato both lycopin 

 and carotin occur. An experimental study of the 

 effects of various conditions upon ripening demon- 

 strates that while carotin is developed under con- 

 ditions of growth differing widely, lycopin is 

 formed only within a limited range of metabolic 

 activity. Temperature and oxygen supply are two 

 of the factors indirectly limiting lycopin develop- 

 ment. In yellow varieties of the tomato ' ' caro- 

 tin" only is found, and in red varieties lycopin 

 formation is precluded by high temperature, yel- 

 low fruits resulting. Irreversible effects are not 

 produced by heat. Red tomatoes seem to contain 

 a factor for redness superimposed upon the factor 

 or factors for yellow, and this conclusion is borne 

 out by breeding experiments. 



A Chemical and Physiological Study of After- 

 ripening of the Bosacew: Sophia Eckerson. 

 The Hawthorn is one of the few seeds where 

 there is known to be a dormancy of the embryo. 

 A period of "after-ripening" is necessary before 

 germination is possible. Food is stored in the 

 embryo as a fatty oil. Neither starch nor sugar 

 is present. The reaction of the cotyledons is acid, 

 but the hypoeotyl is slightly basic. The water- 

 absorbing power of the hypoeotyl is less than 25 

 per cent, of the wet weight. 



There is a series of metabolic changes in the 

 embryo during the period of after-ripening. The 

 initial change seems to be an increased acidity. 

 Correlated with this is an increased water-holding 

 power, and an increase in the activity of catalase 

 and peroxidase. Near the end of the period of 

 after-ripening there is a sudden greater increase 

 in the acidity, and in the water content. All of 



