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T2 



Isfactory and of value,' that the limits of t'^ ^^ccies of both genera 

 should first be well defined. The greatei part of his memoir, there- 

 fore, IS devoted to an account of the morphological characters of the 

 United States species of the two genera. As a result of his studies 

 m this direction, the author recognizes the following species of Gym- 

 nosporangium (in which he includes Podisoma) ; G. Ellisii (Berk.), 

 G. clavariaeforme, DC, G. fiiscum, wa.x. glohosum, Farlow, G. bisep- 

 tatum, Ellis, G. davipes, C. & P., and G. conicum, DC. Of Roestelia 

 he recognizes the follow species : R. botryapites, Schw., R. iransform- 

 ans, Ellis, R. cancellata, Rebent, R. cornuia, Fr., R. lacerata, Fr., R. 

 peniallata, Fr., R. hyahna, Cke., and R. aurantiaca, Pk. It thus ap- 

 pears that we have eight species in each genus, or, throwing out G. 

 comcum (as to the occurrence of which in this country the author is 

 skeptical) and uniting, as is done by many botanists, R. lacerata 

 and R. pentctllata, we have seven species of each. 



Having determined these facts, Dr. Farlow undertook, during the 

 springs of 1876, 1877, 1878 and 1880 a series of cultures of Gymno- 

 sporangium spores on the leaves and young plants of such Pomeae as 

 are usually attacked by Roesteliae ; selecting for his experiments the 

 species G macropus, G. fuscum, var. globosum, G. biseptatum and G. 

 clavipes. The results of these experiments are certainly not calculated 

 to strengthen the faith of those who have relied on the accuracy of 

 the Danish botanist's conclusions. The sowings were succeeded by 

 spermogonia m a very small number of cases— on 10 leaves out of 

 126— and upon only two plants {Amclanchier Canadensis and Cratae- 

 gus tomentosa) OMX. of the seven chosen. Those on Amelanchier fol- 

 lowed the sowing of G^. macropus; but, since that plant supports three 

 species oiRoesteha, it was impossible to say to which one of these it 

 belonged. The spermogonia which made their appearance on Cra- 

 taegus tomentosa followed the sowing of three species of Gymnosporan- 

 gtum--G.macropus, G. globosum and G. biseptatum, yet not one of 

 these is the species which, according to Oersted, ought to produce R. 

 lacerata, which is our common form on Crataegus. Taking into con- 

 sideration the results of these cultures, together with certain facts in 

 regard to the distribution of our species, Prof. Farlow is led to the 

 conclusion that, even granting the general correctness of Oersted's 

 supposition that the Roesteliae are genetically connected with the 

 Gymnosporangta, proof is as yet wanting to show the connection in 

 the case of given species. Furthermore, if it should be shown, says 

 the author in conclusion, that, as appears to be the case with R. 

 auranta, several of our Roesteliae are perennial— a fact true with re- 

 gard to most of our Gymnosporangia—SinA that they grow in regions 

 remo e rom species oi Juniper ut ^n^ Cupressus, then one colTZ 

 he p feeling that any connection between the two genera was prob- 

 ably accidental rather than ^enetic = l^iuu 



Whate 



netic relationship of the two genera here monographed, botanists Ire 

 to be congratulated, at least, that the opening of the question in the 

 present instance, has resulted in giving them so valuable a contribu- 

 tion to the systematic portion of our mycological literature 



