76 PHYSIOLOGY [BoT. Absts., Vol. IX, 



of the solution up to a certain point, and then decreases. An end point in the hydrolysis is 

 not reached without altering the equilibrium of the system, as by changing the temperature 

 and diluting the solution. If judged by the iodine test an end point was obtained, but a quan- 

 titative determination of the reducing sugars did not account for all of the starch. When 

 the enzyme is in suspension some of it is removed by filtering through Whatman chemically- 

 prepared filter paper. Using equal weights of enzyme powder it was found that mycelium 

 grown at 9° hydrolyzed about 4 times as much starch in the same length of time as mycelium 

 grown at 40°C. The enzyme power of mycelium grown at 29 °C. was intermediate between 

 the 2. At these 3 temperatures the best growth of the fungus was made at 29° and the poorest 

 at 9''C. There is "quantitative regulation" of the enzyme. The hydrolyzing power of myce- 

 lium is much greater when starch alone is used as a source of carbon than when glucose alone, 

 or in combination with starch, was employed. However, if grown on sweet potato bouillon , 

 which contains both starch and sugars, a unit weight of the mycelium will hydrolyze more 

 starch than when grown on any of the other combinations. The vigor of growth of the fungus 

 was correlated with the hydrolytic power of the enzyme powder. The results seem to indicate 

 that it is not so much the source of the carbohydrate which influences the quantitative pro- 

 duction of the enzyme as it is the influence which it has on the growth of the fungus on 

 which the secretion of the enzyme depends. — L. M. Massey. 



508. Leoncini, G. Di un'ossidasia vegetale agente sulla florizina. [An oxidase of vege- 

 table origin acting upon phloridzin.] Staz. Sperim. Agrarie Ital. 53: 138-145, 1920. — When 

 wheat kernels are allowed to remain in a solution of phloridzin at a temperature of 15-20°C. 

 these soon become surrounded by a zone of yellow liquid. This zone extends to include the 

 whole solution if the seed are allowed to remain for a few hours longer. The same phenomenon 

 takes place when the seed have previously been sterilized with a 2 per cent CUSO4 solution, 

 or with formaldehyde. The seed of various other Graminaceae weije tried and found to give 

 negative results. The flour of the Triticum seed also gave negative results, while the bran 

 was found to give positive results. The action was stopped when the seed were heated to 

 100°C. for 5 minutes or if the seed were placed in a system from which all the oxygen had been 

 removed by means of a mercury pump. Sterile apple pulp gave a similar result. In a solution 

 of tyrosine, however, no change took place. Beet pulp acted on both solutions, although its 

 oxidizing power upon phloridzin is greater than upon tyrosine. The author concludes from 

 these findings that some plants contain an oxidase capable of oxidizing phloridzin to a yellow 

 substance probably of a quinoid structure, a change which permits the assumption that phlo- 

 ridzin behaves as a true chromogen. — A. Bonazzi. 



509. Mason, T. G. On the inhibition of the invertase in the sap of Galanthus nivalis. 

 Notes Bot. School Trinity Coll. Dublin 3: 105-119. 1920. — Since the depression of the freez- 

 ing point of a sucrose solution is approximately doubled by complete inversion of the sucrose, 

 it seemed probable that an approximate estimate of the sucrose content of the sap of leaves 

 could be obtained by observing the increase in the depression of the freezing point after storage 

 at a suitable temperature. It was found, however, that other factors (one or more) present 

 in extracted sap tended to limit the activity of the enzyme. Changes of a nature not yet 

 understood (possibly H-ion concentration) occurring in extracted juice lead to a clumping of 

 the colloids. It is suggested that the enzyme may be inactivated by adsorption on the coagu- 

 lated colloids. The experiments performed suggest that in cases of sucrose storage in living 

 leaves the activity of the enzyme tending to invert it is regulated by reversible precipitation 

 of the colloid (anti-enzyme). — G. B. Rigg. 



METABOLISM (RESPIRATION, AERATION) 



510. Rockwell, G. E. A study of the gaseous requirements for the growth of various 

 bacteria. Jour. Infect. Diseases 28:352-350. Fig.l. 1921. — The author finds that the growth 

 of some bacteria ordinarily considered to be of the aerobic and of the facultative anaerobic 

 group is in some way favored by CO2. Strict anaerobes cannot use even traces of atmospheric 

 oxygen. — Selman A. Waksman. 



