lamp. The holes were cut with a sterile knife, and after being inoculated 

 were bound up with sterilized tape which had been soaked in parafin. 

 The control canes were treated in a similar manner, but in this case 

 no spores were introduced. On Decmeber 28 these canes were exam- 

 ined. In no instance had the mycelium spread to any extent, except 

 immediately above and below the wound where it had reached the 

 nearest nodes. The affected tissues were a bright red, but the cane 

 exhibited no traces of the rind disease. The controls showed no 

 infection, although the cells around the wound were bright red and 

 the bundles cut through showed gumming in the large vessels. 



Experiment II. — On December 10 four healthy White Transparent 

 canes were inoculated mth iVIelanconium spores from a pure culture 

 at wounds made with a sterile knife as before. Four other canes 

 from the same stool were used as controls. Thirty days afterwards 

 the canes were examined. In all cases the tissues were brownish red 

 above and below the wounds, but no difference was evident between 

 the inoculated canes and the controls in this respect. On examining 

 the inoculated canes it was found that the mycelium of the fungus 

 had in all cases spread in the tissues immediately above and below 

 the wounds as far as the nearest nodes, but it could not be traced 

 beyond the vertical column of tissue containing the wound and 

 bounded by the nodes above and below this aperture. 



Experiment III. — On December 19 four healthy White Trans- 

 parent canes were doubly inoculated — at wounds in an upper and a 

 lower internode — ^^ath actively growing mycelium of the fungus from 

 pure cultures. Four other canes were used as controls. On Jan- 

 uary 22 the results were almost identical with those obtained above. 



Experiment IV. — The same experiment was made using only 

 spores from a pure culture instead of the mycelium. The same re- 

 sults were obtained. 



Howard concluded as a result of his studies that Melanconium 

 cannot be considered as the cause of the "rind" disease. He appears 

 to have shown that Melanconium is not an active parasite, but it is 

 not clear that he has demonstrated this fungus to be only a sapro- 

 phyte. In fact his inoculations rather point to Melanconium being 

 a wound parasite. Howard appears to be assuming that the rind 

 disease is caused by an active parasite, for the proof of which he 

 presents no facts whatever. 



CAUSE OF THE RIND DISEASE. 



In discussing tlie cause of the rind disease it will be well to 

 review briefly the symptoms of this trouble first. As mentioned in 



37 



