1902.] NATURAL SCIEN'CES OF PHILADELPHIA. 463 



tigated more particularly the pathological symptoms produced in 

 the host plants by the European species of Gymnoqyorangium, 

 viz., G. junipermum, O. clavarueforme, G. sabime, and in a gen- 

 eral way, with imperfect material at his disposal, the pathology 

 of the American species of Gymnosporangium, viz., G. Ellkii, G. 

 biseptatum, G. clavipes, G. macropus. He investigated the changes 

 produced in the bast, the cortex and the wood of Juniperus nana 

 and J. communis by Gymnosp)oranyium juniperinum {conicum); of 

 J. communis by G. clavariceforme ; of J. sabina by G. sabince. 

 He investigated in a most general manner the disease conditions 

 induced by the American species of this genus of fungi. Hailig* 

 described the botanical characters of the following species of Gym- 

 nosporangium : G. conicum (^juniperinum'), G. clavarueforme, G. 

 sabince (fusciim), G. tremelloides. ■ Frank^ described in a general 

 way the botany and pathology of Gymnosjyorangium fuscum, 

 G. confusum, G. clavariceforme, G. conicum, G. Ellisii, G. macro- 

 pus, G. biseptatum, G. clavipes, G. globosum, G. nidus-avis, 

 G. Cunning hamiamim. Plowright'" obtained some unexpected 

 results by cultures made with the teleutospores and secidiospores of 

 the three European species of Gymnosporangia, viz., G. clavarice- 

 forme, G. conicum, G. fuscum, enlarging materially the list of 

 plants upon which the Roestelia of these plants are found. Thax- 

 ter," by numerous culture experiments, succeeded in most cases in 

 working out the life -histories of the American species of the genus 

 Gymnospiorangium, by connecting the recidial stage on rosaceous 

 plants with the teleutosporic stage on various coniferous trees. San- 

 ford^^ studied the structure of the twigs of the red cedar with refer- 

 ence to the formation of the cedar apple. He made a detailed 

 microscopic study of the cedar apple swelling, the spores and the 

 spore-bearing filaments. A brief mention of these articles is 

 suflficient to draw attention to the fact that very little work has 

 been done on the pathological conditions produced by the American 

 species of Gymnosporangium. 



^ Hartig, The Dueases of Trees (Enslisli translation), 1894, p. 157. 



'■•Frank:, Die Pilzparaaitaren KrankheUeii der Pflamen, 189G, II, pp. 

 170-184. 



'"Plowrioht, British Heteroecious Uredines, Journ. Linn. Soc. Bot., 

 1888, XXIV, p. 93. 



11 TiiAXTER. Bot. Gaz., 1889, XIV, p. 163 ; Conn. State Exper. Stat. 

 Report, 1891, p. 161. 



i'Sanford, Annals of Botany, 1887, I, p. 263. 



