:41'4 Alfred J. Eivavt : 



sence of bacteri;i and fung:!, starch cells could still be found after 

 three weeks c|uite unaffected and undissolved. Apparently the 

 poison inhibiting diastatic action in such cases is a metallic one, 

 firmly adhering to the starch grains. Actual tests showed 

 that the addition of one gram of arsenate of lead to 1000 grams 

 of starch completely protects the starch grains from the corro- 

 sive action of ferments, if a thorough mixture is made prior to 

 adding the solution of the ferment, and this although arsenate 

 of lead is a comparatively insoluble poison. 



Apples affected with natural bitter pit were inoculated with 

 the hyphae of Penicillium, and other undetermined saprophytic 

 fungi, taken from apples undergoing soft rot. The hyphae grew 

 freely in the sound pulp, but usually distinctly avoided the bitter 

 pit areas, at first growing right past or around them before 

 invading them laterally. The starch grains in the bitter pit 

 areas remain partially undissolved long after any starch grains 

 which may be present in healthy pulp cells have disappeared. 

 Obviously the bitter pit areas contain a higher percentage of 

 poison, and the fact that the hyphae will ultimately grown into 

 them is not surprising, since they also grow freely in apples 

 poisoned throughout by mercuric chloride or copper sulphate. 

 Similar results were obtained with artificial bitter pits produced 

 by 1 per 100,000 concentrations of mercury and lead, and to a 

 less extent by copper. 



If the poison in question were not the originating cause of 

 the bitter pit, but were produced by the secondary changes 

 during the development of the pit evidenced by the change of 

 colour, by the modification of the cell wall and by the disorgani- 

 sation of the protoplasmic cell contents, then it should always be 

 repellent to saprophytic fungal hyphae. ' xlrtificial bitter pits 

 produced by minimal toxic concentrations of metallic poisons are 

 penetrated by fungal hyphae as readily as, or even more readily 

 than, the healthy pulp tissue or natural pit tissue, and the pits 

 produced by formaldehyde ammonia, potassium and magnesium 

 in moderately toxic concentration, exercise a distinct attraction 

 upon the fungal hypliae. Evidently, therefore, the secondary 

 changes during the development of bitter pit do not result in 

 any noticeable production of distinctly toxic materials. In 



