62 CARNEGIE INSTITUTION OF WASHINGTON. 



pigments follows from the great and irregular disproportion which 

 has been found to exist between the chlorophyll-content and photo- 

 synthetic activity. The experiments on this subject have shown that 

 the relation between photosynthesis and respiration is an intimate 

 one, and that this relationship holds both on an ascending and on a 

 descending rate of either process. The experiments are now being 

 directed to determine whether this relation is actually on an energetic 

 basis or whether it is of a chemical nature, i. e., dependent upon 

 certain components of the protoplasm, which vary in amount or with 

 the metabolic activity. Whether the former state exists can be de- 

 termined by a study of the temperature coefficient of photosynthesis 

 under varying conditions of carbohydrate-content and respiratory 

 activity. The possible chemical dependency may perhaps be de- 

 termined by a study of the enzymatic relations, more especially of those 

 enzymes which are active in the respiratory activity, catalase, and 

 peroxidase, and which, from the data thus far obtained, also function 

 as a step in the photosynthetic process. Both of these lines of investi- 

 gation are being pursued, for which the constant-temperature rooms of 

 the new laboratory at Carmel offer excellent facilities. 



Reduction of Pentose Sugars, by H. A. Spoehr and J. W. E. Glattfeld. 



For the continuation of these investigations (Carnegie Inst. Wash. 

 Year Book 1920, pp. 64-66), Dr. J. W. E. Glattfeld, of the University 

 of Chicago, again spent January, February, and March as a Research 

 Associate at the Desert Laboratory. In order to simplify the usual 

 cumbersome and time-consuming procedure of carrying out reducing 

 reactions with large quantities of sodium amalgam, a rotary agitator 

 was devised. This contrivance, driven at a very high speed, accom- 

 plished the mixing of several kilograms of sodium amalgam witJi the 

 aqueous sugar-solution to a thick colloidal mass. With the agitator 

 and by means of suitable cooling and the control of acidity of the 

 mixture, the time of the reaction was diminished to half of that ordi- 

 narily required, and the amount of amalgam necessary to reduce a 

 given quantity of sugar w^as also diminished. By this means sev- 

 eral hundred grams of pure xylit were obtained. All attempts at 

 getting the xylit to crystallize have failed, however, nor has it been 

 possible to obtain a quantitative reduction of the sugar; there is 

 always formed a small quantity of sugar gum. This does not reduce 

 Fehling's solution, but on treating with hydrochloric acid gives a 

 decided reduction. The composition of this gum has not yet been 

 established. The xylit was dehydrated by means of anhydrous for- 

 mic acid. This mixture was distilled, and besides gaseous products, 

 water, and formic acid, it yielded a volatile oil which on account of 

 its ease of polymerization it has not been possible to identify. 



