DUFRENOY: false WITCHES'-BROOMS in ERICACEAE 531 



unedo. We were able, however, to separate from fresh tissues, 

 ground in water and microsubHmated, volatile glucosides which 

 crystallized in two separate forms. Some of the crystals stained 

 yellow after being treated with vapors of ammonia for half an 

 hour. 



The cells containing glucosides stain direct in sections of 

 tissues treated with nitric acid (Molisch's test I) We could 

 thus prove the glucoside to be present in all vegetative sound 

 tissues of A. unedo, while it is lacking from cells infected by Gloeo- 

 sporium in false witches'-brooms. (See table 2). 



In infected cells where the glucoside disappears, the brown 

 pigment appears, and it may be supposed that the fungus 

 Gloeosporium secretes an enzyme which brings about the hy- 

 drolysis of the glucoside to glucose and hydroquinone, the latter 

 being oxydized to the brown pigment. 



The actual production by fungi of an enzyme able to effect 

 the hydrolysis of arbutin has been determined by Rayner ('15) 

 for the endophyte of Calluna by transferring pure culture mate- 

 rial to tubes containing a 0.5 per cent solution of arbutin. In- 

 fected tubes soon showed a browning of the solution, while con- 

 trol tubes remained colorless. 



CONCLUSIONS 



False witches'-brooms of Ericaceae may sometimes show a 

 reduction of transpiration, a feature which may be viewed as 

 advantageous. But, as false witches'-brooms possess very low, 

 if not fully inhibited power of assimilation, and are shorter- 

 lived than are healthy shoots, they cannot be interpreted as 

 symbiotic organs. 



Morphological variations due to infection are very shght, 



but such as are present should be viewed in the light of meta- 



phanic (as concluded by Potonie, '12) rather than progressive 



variations. 



BIBLIOGRAPHY 



BoTJRQUELOT, Em. et FicHTENHOLZ, A. Application de la methode hiochimique a 



la recherche du saccharose et des glucosides dans quelques Ericacees. 



Journ. Pharm. Chim. VII, 8: 158-164. 1913. 

 Combes, Raoul. Recherches biochimiques experimentales sur le role physi- 



ologique des glucoside chez les vegetaux. I. Etude preliminaire. Rev. 



Gen. Bot. 30: 70-92. 1918. 



