1 882.] Botany. 1005 



on the washing away of the soil on the tops of high mountains, 

 and the relation of the " timber line " to these facts, and suggested 

 that in theories of the disappearance of forests both in the past and 

 in the present, the agency of water as well as of climate should 

 not be overlooked. It was not this that Professors Leidy, Heil- 

 prin, Koenig, and Redfield opposed, but in their experience they 

 had found that so far as the question of the " timber line " was 

 concerned, climatic influences had as much, if not more to do in 

 deciding it, than the mere washing away of the soil by. rains or 

 melting snows. — Thomas Median, Gcrmantoivn, Pa. 



On the Hetercecism of the Uredine.e.— Charles B Plowright 

 recorded last year in the December number of Grcvillea, the 

 results of a series of experiments upon the barberry cluster cup 

 (Alcidiuw berberidis) and wheat rust {Puccinia graminis), which 

 led him to " differ from the eminent botanists abroad who do 

 accept the hetercecism of /'.•/. -inia .. ramiiiis as established beyond 

 question." This year he made another series of experiments, the 

 results of which he gives in the September Grevillea as follows : 

 "This year another series of cultures was instituted, in which the 

 promycelium spores [sporidia] of Puccinia graminis were sown 

 upon young barberry plants, with the unvarying result of pro- 

 ducing the V-Hcidium,' the check plants remaining free from the 

 fungus. Young wheat plants, which were kept continuously cov- 

 ered by bell glasses from the time they were first sown till the 

 experiment was concluded, were also found, when infected with 

 ripe Aicidium bcrbcridis spores, to become infected with Uredo, 

 while similar plants not so infected remained healthy," 



The experiments were so conclusive that Mr. Plowright, who 

 entered upon them " biassed against " the doctrine of hetercecism, 

 now fully accepts it. 



Note on Gerardia.— It may be worth recording that Gcrardia 

 pediatlaris L., although blooming profusely about Providence this 

 season, yet owing, perhaps, to the long-continued drouth is not 

 nearly so much frequented bv humble-bees as usual. Indeed, 1 

 notice more honey-bees about the plants. The consequence is, 

 that much fewer flowers are perforated in the manner I have be- 

 fore described. In a half hour's careful observation I did not see 

 one humble-bee avail himself of the holes already cut nor make 

 a new perforation. All entered by the open mouth of the enrol a. 

 There would seem then to be no necessary imp diment .to then- 

 means of ingress. Does not the d ^n^ ,\ muni* r of seekers 

 account for the legitimate action of the few ? Absence ot active 

 competition renders it unnecessan for th n mini n < bees to 

 adopt a burglarious habit.- IK IV. Bailey, Bvoivn University, Sept. 

 4, 1882. 



