April, 1920] I'm MH.OCY 177 



middle lamellae bright red and tin- secondary lamellae green, the gum showing greater or leae 

 attraction for one or the other stain. — In relation to various dJ and injuries gumming 



was studied in a variety <>f woody plants. It is concluded thai the pi quite v oeral 



in woody plants and is due to the activities of an enzyme, the symogerj "f which is constantly 

 present. Certain stimuli induce the formation of large quantities of the ensyme «*"«"■ 

 liquefaction of the pectic substances, which are deposited in the tissues or exuded M gum. 

 As a means by which plants are protected from serious injury through BUlface wounds or fun- 

 gous attacks gum formation is considered important. A bibliography is appended. — T. //. 

 McHatton. 



METABOLISM (RESPIRATION) 



1231. Irwin, Marian. Comparative studies on respiration. VI. Increased production of 

 carbon dioxide accompanied by decrease of acidity. Jour. Gen. Physiol. 1: 399-403. 1919. — 

 The petals of Salvia involucrata and S. splendens were employed in this study. The author 

 finds that ether increases the consumption of oxygen in the petals of these plants as well aa 

 producing an increased production of CO2. There is also an accompanying decrease in the 

 acidity of the cells. — J. M. Brannon. 



1232. Northrtjp, J. H. The effect of various acids on the digestion of proteins by pepsin. 

 Jour. Gen. Physiol. 1: 607-612. 1919. — The author found that in equal hydrogen ion con- 

 centrations the rate of pepsin digestion of gelatin, egg albumin, blood albumin, casein, and 

 edestin is the same in the solutions of hydrochloric, nitric, sulfuric, oxalic, citric, and phos- 

 phoric acids. The rate of digestion of all the protein, with the exception of gelatin, was 

 decreased by acetic acid. There was no evidence of antagonistic salt action. The aggre- 

 gation of the protein and the viscosity of the solution have no marked influence on the rate of 

 digestion of the protein. — J. M. Brannon. 



1233. Rockwood, Elbert W. The effect of neutral salts upon the activity of ptyalin. 

 Jour. Amer. Chem. Soc. 41: 228-230. 1919. 



1234. Sherman, H. C., Florence Walker, and Mart L. Caldwell. Action of enzymes 

 upon starches of different origin. Jour. Amer. Chem. Soc. 41 : 1123-1129. 1919.— When wheat, 

 maize, and rice starches are purified by washing with very dilute alkali, they show the same 

 digestibility. When they are acted upon by the same kind and amount of amylase, they are 

 all transformed into reducing sugar at essentially the same rate. "This is true whether the 

 digestive agent be saliva, pancreatin, purified pancreatin, amylase, malt extract, purified 

 malt amylase, taka-diastase, or the purified amylase of Aspergillus oryzae." Fatty substances 

 hindered the hydrolysis of some of the cereal starches, especially maize. — J. M. Brannon. 





1235. Sherman, H. C, A. W. Thomas, and M. E. Baldwin. Influence of hydrogen ion 

 concentration upon enzymic activity of three typical amylases. Jour. Amer. Chem. Soc. 41 : 

 231-235. 1919. 



ORGANISM AS A WHOLE 



1236. Brann, F. R. Factors concerning the drop of immature citrus fruit in central Cal- 

 ifornia. Monthly Bull. Comm. Hortic. California 2: 74-75. 1919.— See Bot. Absts. 3. Entry 

 1057. 



1237. Dawson, Andrew Ignatius. Bacterial variations induced by changes in the com- 

 position of culture media. Jour. Bact. 4: 133-148. 1919.— Variations in bacteria were indu 

 by changing the environment in which the bacteria live. Cultures of Bacillus coli were gr< »wn 

 on 8 different types of media for 200 generations and then tested for variation as to the chem- 

 ical composition, including relative amounts of water and volatile matter, ash, sulphur, 

 phosphorus, calcium, total nitrogen, amino-nitrogen, proteins, fats, and carbohy.in. 



BOTANICAL ABSTRACTS, VOL III, NO. 4 



