19171 AGRICULTUEAL CHEMISTEY — AGROTECHNt. 315 



combined in nature exert a stabilizing and perhaps otherwise favorable influence 

 on the curative nucleus, but do not in themselves possess the vitamin type of 

 physiological potency. Accordingly it is believed that while partial cleavage of 

 vitamins may result only in a modification of their physiological properties, by 

 certain means disruption may go so far as to effect a complete separation of 

 'nucleus' and 'stabilizer,' and if it does so will be followed by loss of curative 

 power due to isomerization." 



The terminology introduced by McCollum and Kennedy (E. S. R., 35, p. 166), 

 based on the solubility of the substances isolated, is considered by the authors 

 to be an unfortunate choice because of the influence of various other substances 

 on solubility, and in their discussion they retain the word vitamin, as employed 

 by Funk. 



On the products of the action of certain amylases upon soluble starch, 

 with special reference to the formation of glucose, H. C. Sherman and P. W. 

 PuNNETT {Jour. Amer. Chem. Soc, S8 {1916), No. 9, pp. J877-i 885). —Experi- 

 ments are described from which it is concluded that any of the amylases tested 

 (pancreatic, malt, and taka-diastase) may form some glucose. Under the con- 

 ditions which prevail in the usual determinations of diastatic power, however, 

 the yield of maltose so far predominates as to justify the custom of calculating 

 the reducing powers of the digestion products as due to maltose alone. 



Experiments upon starch as substrate for enzym action, H. C. Sherman 

 and J. C. Bakee {Jonr. Amer. Chem. Soc, 38 {1916), No. 9, pp. 1885-190Jf) .— 

 " Dispersions of commercial potato starch in water or of purified potato starch 

 in water containing a small amount of electrolyte (sodium chlorid) have been 

 separated by centrifugal force into a heavier, very viscous, opalescent layer 

 containing the more abundant, less soluble component of the starch (Meyer's 

 a-amylose, Maquenne's amylopectin), and a lighter, limpid solution containing 

 the less abundant, more soluble component (Meyer's )3-amylose, Maquenne's 

 amylose)." 



It is indicated that the centrifugal method described for the separation of 

 the starch components does not completely separate either component from 

 the other, but affords a means of approximate separation in which the danger 

 of contamination, denaturization, or retrogradation is minimized. The method 

 is M^ell adapted to the study of the effects of the different amylases. 



" Pancreatic amylase both in commercial and in highly purified form pro- 

 duced reducing sugar more rapidly from /3-amylose than from a-amylose, auto- 

 claved starch, or Lintner soluble starch, the last three giving very similar 

 results when used as substrate for this enzym. Not only does the /3-amylose 

 substrate show a larger yield of maltose at each of the various time intervals 

 tested, but the initial speed of hydrolysis is better maintained with this sub- 

 strate than with either of the others. 



" Purified malt amylase shows in the earlier stages of its action a somewhat 

 greater yield of maltose from a- than from j3-amylose. As the digestion pro- 

 ceeds the saccharogenic action of this enzym upon a-amylose becomes slower, 

 while its action upon j8-amylose is well sustained, so that in cases in which the 

 hydrolysis proceeds to the production of more than half the theoretical yield 

 of maltose the final result shows a greater saccharogenic action upon /3- than 

 upon o-amylose. The results obtained upon autoclaved starch and Lintner solu- 

 ble starch are very similar to those found with a-amylose." 



Taka-diastase was found to digest Lintner soluble starch, autoclaved whole 

 starch, and a-amylose at about equal rates, and /3-amylose at a somewhat higher 

 rate. The action of pancreatic or malt amylase is better sustained than that of 

 taka-diastase upon the /3-amylose substrate. " This relatively early falling off 



