STUDIES IN THE GENUS GYMNOSPORANGIUM—I. 
NOTES ON THE DISTRIBUTION OF THE 
MYCELIUM, BUFFER CELLS, AND 
THE GERMINATION OF THE 
AECIDIOSPORE 
B: ©: DODGE 
Columbia University 
‘The sporophytic mycelium of different species of Gymnosporangium 
exerts an influence in connection with the growth of the tissues of the 
cedar hosts which is manifested in a variety of ways. It is not clear 
just why one species will cause the formation of a rather fleshy gall, 
while another species will lead to the development of a witch’s-broom 
or a hard, woody burl. A study of the interrelationships of host and 
parasite, especially the more intimate association of the hyphae and 
the host cells may help to solve some of these interesting questions. 
I wish to report briefly at this time the results of some studies 
made to determine: (1) the distribution of the mycelium in an infected 
leaf; (2) the possibility of its spread from leaf to stem; (3) the degree 
to which it spreads up and down; (4) its distribution in wood, phloem 
and cortex; (5) the distribution of haustoria. Four-nucleated 
aecidiospore germ-tubes of Gymnosporangium transformans, and the 
formation of buffer cells in the teleutospore sori of G. fraternum and 
G. transformans will be noted. 
Farlow! determined the general distribution of the mycelium in the 
host for a number of American Gymnosporangia and described with 
considerable clearness the primary effects of the parasites on the 
tissues of the host plants. He found that the burls on Chamaecyparis 
infected by G. biseptatum are probably the result of a stimulation of 
the cambium by the hyphae mainly distributed in the cambium region. 
There appeared to be very little in the nature of a deleterious effect 
of the parasite on this host. It was evident to him, however, that 
the actual presence of mycelium in a given tissue is not necessary 
to account for distortions or abnormalities. In G. Ellisii the fungus 
interferes with the normal growth of the host, producing proliferations 
and swellings of the stems and branches. This may be due to a dis- 
turbance in the nutritive processes, the primary cause of which may 
‘Farlow, W. G. The Gymnosporangia or Cedar Apples of the United States. 
Am. Mem. Boston Soc. Nat. Hisc. 1-38. pl. 1, 2. 1880. 
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