THE WATER-RELATION OF PUCCINIA ASPARAGI. 
A CONTRIBUTION TO THE BIOLOGY OF A PARASITIC FUNGUS. 
RALPH E. SMITH. 
(WITH TWENTY-ONE FIGURES) 
WHETHER the use of the term ‘“‘ecology” would be consistent and 
proper throughout the present article, the writer must confess his 
inability to decide. With plants of independent existence ecology 
has become a well-defined branch of botanical science, but when 
complicated with the phenomena of parasitism there must be dis- 
tinguished two fairly distinct classes of life-relations; those which act 
upon the parasitic organism directly, and those which affect it, even 
more decidedly perhaps, in a secondary or indirect manner through 
their effects upon the host-plant. “‘ Biology,” in the European sense, 
seems on the whole a more fitting term for the present purpose; 
since at many points it is difficult to say whether we are considering 
the relation of the parasite to its environment, or to its host’s environ- 
ment, or whether its host is its environment. The subject is one of 
ecology in the broadest sense, yet a distinction must be made between 
the relations of an organism to natural influences, and its relations 
to the effects of perhaps the same influences upon another organism 
upon which it lives as a parasite. The fungus has no soil-relation, 
of course, but its connection with the host-plant is much more than 
this, though corresponding to a certain ev‘2nt. Without extended 
discussion on this point, it will suffice to say that it has seemed to 
the writer very desirable to establish upon a systematic basis the 
relations existing between parasitic fungi in general and the various 
influences exerted upon them in nature, either directly or acting 
through the medium of the host-plant. While many scattered 
observations of this kind exist, very little definite work has been done 
in establishing general principles or in drawing definite conclusions. 
The observations contained herein are offered as a modest contribu- 
tion in this direction. 
It is well established in a general way that the development of 
1904] 19 
