1004 
Journal of Agricultural Research 
Vol. V, No. 22 
have been especially confused, and on account of their interest in North 
America they will be discussed together in this paper. In order to make 
the situation clear, a review of the literature of these rusts with refer¬ 
ence to their occurrence in Japan as well as in the United States will 
be given. 
INVESTIGATIONS IN JAPAN 
From 1897 to 1899 Shirai (7) 1 conducted infection experiments in 
which he claimed to show that Roestelia koreaensis was genetically con¬ 
nected with Gymnosporangium japonicum Sydow. He succeeded, in 
several different experiments, in obtaining the development of typical 
aecia of R. koreaensis on the leaves of Pyrus sinensis by exposing them to 
infection from germinating telia on Juniperus chinensis. Shirai stated, 
however, that in Japan the telia of G. japonicum occur not only on the 
trunks and branches, as the original diagnosis of Sydow states, but also 
on the leaves of the juniper, and he described and figured both stages 
(7, pi. 1, fig. 19 and 22). 
Ito (4) recently called attention to the fact that Japanese mycolo¬ 
gists have for some time considered that the forms which occur on the 
stem and leaves of Juniperus chinensis are not the same species. He 
also recorded the results of infection experiments in which the telio- 
spores of the stem form were sown on Pyrus sinensis , Amelanchier asiatica , 
and Pourthiaea villosa , with infection only on the last. The resulting 
aecia proved to be typical of Roestelia photirviae P. Henn. Referring to 
the leaf form, Ito further stated that he considered it to be G. Haraeanum 
Syd. arid that G. asiaticum Miyabe is synonymous. Miyabe and Yamada 
(6) have recently shown by infection experiments that G. asiaticum t 
which occurs on the leaves of /. chinensis , has for its secial stage a 
species of Roestelia on Pyrus sinensis , Cydonia vulgaris , and Cydonia 
japonica. Hara (3) has also recently shown by infection experiments 
that G. Haraeanum has for its aecial stage R. koreaensis on Pyrus sinensis . 
From the above it would appear that Shirai had both forms, Gymno¬ 
sporangium japonicum and G. Haraeanum y mixed in the material which 
he used for inoculation and that his successful results on the pear were 
due to infection by the sporidia of the leaf form, G. Haraeanum (G. 
asiaticum) , and not of the branch form, G. japonicum , as was supposed. 
OCCURRENCE IN AMERICA 
Clinton (1) reported the occurrence in 1911 of Gymnosporangium 
japonicum on imported plants of Juniperus chinensis in Connecticut. 
He also found the two forms on stems and leaves and followed Shirai 
in considering them identical. Long (5), after a study of Clinton’s 
material, called attention to the difference between the two forms and 
described the leaf form as G. chinense , considering it distinct from G. 
1 Reference is made by number to “Literature cited,” p. 1009. 
