43 



ance, and seemed to be struggling for existence. A close inspec- 

 tion showed that many of them were affected by a parasitic fungus, 

 Uromyces Polygoni. On one side of this patch, and continuous 

 with it, was one composed of taller, more healthy looking plants. 

 These were entirely free from the fungus, thus indicating that the 

 weakness of the plants in one patch had favored the development 

 of the disease, while the strength of the plants in the other had 

 resisted it. It might be said by the supporters of the other claim 

 that the dwarfed and weak condition of the affected plants was due 

 to the presence of the fungus and not the predisposing cause of its 

 presence. To one accustomed to observe this fungus, such an 

 assertion would carry but little weight. But if we should admit 

 the truth of this assertion, how should we explain the presence of 

 the dwarf but unattacked plants in this patch ? 



In low ground near the lake shore at Port Henry, were nimierous 

 seedling plants, apparently of the discoid tickseed, Coreopsis 

 discoidea. This ground had been overflowed in time of high water, 

 and when the water receded it left numerous heaps of small sticks, 

 bits of bark and other floodwood. Many of the seedling tickseeds 

 were growing on these heaps of rubbish where there was little or 

 no soil to afford nutriment to their roots. Others were growing on 

 the ground about them, having their roots imbedded in and 

 nourished by the soil. The plants growing on the floodwood were 

 in many instances infested by a parasitic fungus, Peronospora 

 Halstedii; but not a single affected plant could be found among 

 those whose roots were in the soil. In this case the better 

 nourished plants had escaped infection, although as much exposed 

 to it as their less favored companions. Possibly there may be 

 cases in which plants are liable to the attacks of parasitic fungi, no 

 matter how strong and vigorous they may be, but it is clear that 

 this can not be a rule without exceptions. Instances are not want- 

 ing to show a greater susceptibility to attack in weak than in 

 strong and well fed plants. Those who are accustomed to collect 

 specimens of parasitic fungi soon learn, almost unconsciously, to 

 look for them, either among feeble and starved plants or among 

 those of unusually rank and luxuriant growth. 



Very respectfully submitted 



CIIAS. II. VVXK 

 Albany, December 15, 1886 



