New York Agricultural Experiment Station. 535 



spreading toward the tip, and frequently, young lateral shoots 

 would he completely killed by it. Under the microscope it proved 

 to he quite dijfforent from the Exohasidium. Prof. Peck, to whom 

 it was referred, pronounced it a new species of JRamularia and 

 named it Raimdaria cylindriojpsis. 



YIT. ^INOCULATION EXPERIMENTS WITH GYMNO- 

 SPORANGIUM MACPOPUS, LK. 



The family of true rusts, JJredinem, is very interesting to tlie 

 mycologist and important to the agriculturist. It contains about 

 twenty-seven genera and a multitude of species all of which are 

 strict parasites living within the tissues of their hosts. Several of 

 the species produce destructive diseases in cultivated plants; as ex- 

 amples, note the rust of wheat, oats and other grasses {Puccinia 

 graminls, Pers.) , blackberry rust {Caeoma liuninatum, Schw.), and 

 cai-uation rnst {Uromyces caryophyUinus^ (Schrank) Scha'ter). 

 Thus far, all atteuipts to cultivate the rusts upon artificial media 

 have failed. Consenuentl3% the life histories of . some species are 

 imperfectly known. The determination of the life histories of some 

 species is made yet more difticult because of the fact that they do 

 not complete their development upon a single species of host -plant, 

 but inhabit different species at different stages in their development. 

 The life history of the common wheat rust, Puccinia grainiis^ so 

 frequently used to illustrate this peculiarity of rusts, is so familiar 

 to readers of botanical literature that it is unnecessary to repeat it 

 here. It is sufficient to state that wheat rust has three stages, two of 

 which are found upon the wheat or some other grass plant and the 

 third upon the common barberry {Berber is). 



The species of Gymnosporangimn belong to this class of pleomor- 

 phic rusts. There are two forms, representing two stages in the 

 development of the fungus. Until about ten years ago these two 

 forms were supposed to be distiuct species and were given separate 

 names. The Gymnosporangium form (cpnsidered to be the higher 

 form) inhabits, exclusively, species of the Ciipressineae^ a group of 

 the family of cone- bearing trees, Coniferae. The other form has 

 received the name Roesielia. It is found on the apple and allied 

 plants belonging to the tribe Pomeae of the family Rosaceae. 



*By F. C. Stewart and G. W. Carver. Read before the Iowa Academy of Sciences, Des 

 Moines, Iowa, January 2, 1896. 



