32S TWENTY-FIU8T REPORT. 



AH varieties of apples tested resix>iided quickly. Clayton, Northern Spy, 

 Arkansas Black, Grimes Golden, Wealthy, Maiden Blush, Ilyslop (-rah were 

 used successfully. The character of the skin is very iun)ortant in regulating 

 the manifesting of the effects. A thick, corky skin like that of the potato, 

 seems to prevent injury. When fruit is exposed to the fumes it quickly 

 becomes coated with the only greasy material mentioned by Chivers. This 

 is evidently phenol condensed upon the skin. It would seem that the waxy 

 coat on the fruit was the best index of the likelihood of phenol sensitiveni^ss. 



Very young green apples did not blacken during the summer although 

 repeatedly tested. Green ai)ples placed alongside of more mature apples did 

 not blacken, although the rii>er apples blackened slowly. The best response 

 comes with the more mature specimens, tested in the fall and winter, but a 

 rii>ened mealy apple in late spring does not respond well. The calyx end of 

 the apple blackens first and presents the most characteristic discoloration. 

 The waxy cuticle of the fruits seems to function to collect or condense the 

 fumes, this part becoming greasy very quickly when exposed to strong phenol. 

 It is surmised that the wax of the skin is important in bringing about the 

 phenol reaction, serving as it does to collect the chemical. 



The vascular .system seems to respond more quickly than the pulp of 

 I 111' apple and colors a deeper black, the flesh taking on a brownish-black 

 color. Flesh discoloration lags about two days behind the skin discoloration. 



DISCUSSION. 



This i)aper is a preliminary report npcm the effect of phenol uiion certain 

 fruits. It is intended merely to record the results of the tests ratlier than t(» 

 explain the mechanism of the reaction. It may be remarked that the experi- 

 ments performed sliow that the response is that of living matter, not dead 

 nuitter. The reaction is connected with living cells and is not the mere chem- 

 ical efilect of one substance uiH)n another. The failure of green apples to 

 lilacken brings a problem of permeability and protoplasmic composition. The 

 response of mature cells and the failure of the dead cells in the mellow 

 apples to respond point to the possit)ility of this substance furnishing a cri- 

 terion for active and for dead cells. 



The minute quantities necessary for tlie reaction is also significant. 

 When we consider the most unweighable deposit from a weak solution being 

 able to blacken an entire apple and to communicate this effect from cell to 

 cell until the entire apple is a brown-black mass with a jet black skin, it is 

 evident that we are dealing with a substance which acts upon the enzymes. 

 Since no tests in which specific enzymes have been isolated have as yet been 

 made (mly a hypothesis can be advanced to account for the blackening. It 

 may be that the phenol reacts with .some <»xydizing enzyme such as tyrosinase 

 producing the blaekeiiiiig. Fuither work is planned t<» develop this particular 

 suggestion. 



