Nov. i8. 1918 Physiological Studies of Normal and Blighted Spinach 383 



photosynthetic function. This condition recalls that of tobacco leaves 

 when "mature" for cutting. The color changes to a more yellowish 

 green, the leaves take on the brittle character seen in the diseased spinach 

 and like it become gorged with starch. 



It would hardly be safe to assume that photosynthetic activity is not 

 impaired in the blighted plants in spite of the accumulation of carbo- 

 hydrates. It is quite possible that impairment may be the case and 

 that accumulation results from some interference with carbohydrate 

 utilization. 



In view of the destructive action of oxidases on diastatic enzyms, 

 reported by Woods (57) in the case of tobacco mosaic, it was thought 

 possible that here a somewhat similar situation was present. Since 

 Bunzell in his investigation on this subject found the oxidase reaction 

 with most reagents to be somewhat more intense in the diseased material, 

 both leaves and roots, than in normal samples, it was thought necessary 

 to determine the comparative diastatic activity of juices from these two 

 types of material. The fresh leaves, after being ground in a mortar, were 

 placed in a flask having a volume of 250 cc. and digested for 24 hours 

 with 100 cc. of glycerin in an ice box at a temperature of about 10° C. 

 This was then made up to volume, strained, and 50 cc. of the solution 

 was added to 25 cc. of i per cent soluble starch. Controls were made 

 in the same way from each sample to which no starch paste was added. 

 One cc. of toluol was added to each flask to prevent the action of micro- 

 organisms. All preparations were allowed to stand at 30° C. for 48 

 hours, after which they were removed, cleared with lead acetate, made 

 up to 100 cc. and filtered. The data given in Table II show the quan- 

 tity of reducing sugar present in the preparations containing starch 

 paste in excess of the controls from the same samples. 



Table; II. — Diastatic activity in normal and in blighted spinach 



o Extracted with larger volume and calculated to the same basis as the others. 



