THOMAS: INFECTION OF APIUM GRAVEOLENS 5 
fungus in America expresses uncertainty as to the identity of the 
species but includes a description of the fungus and states that if 
it is a new species it “might be named Septoria Apii.”” Rostrup 
(33) in Denmark (1893) published the same name apparently 
independently. Briosi and Cavara (3) published their variety 
of Septoria Petroselini in 1890 (appeared 1891). Klebahn (17) 
reviewed the situation at some length, examined the exsiccati and 
decided in favor of the name S. Apii Rostr. Quanjer and Slagter 
‘in Holland (30) and Coons (8) in this country have treated the 
fungus under the same name. It will be noted later that the 
fungus I have studied, so far as it has been tested, does not produce 
infection on parsley either in the greenhouse or in the field. It 
has already been pointed out that no report of cross inoculations 
has been found in the literature, although a number of authors 
have taken it for granted that the form on parsley and the one 
on celery are identical. Therefore, whether or not it be granted 
that the failure to cross infect between these closely related hosts 
be considered ground for making a specific distinction, I shall 
continue to use the name S. Apii Rostr., especially since it is 
already quite widely distributed in the literature. The question 
of nomenclature may well be left till our knowledge of the life 
history of the fungus is completed by the discovery of an ascigerous 
stage. : 
CHARACTER OF THE SPOT 
The spots on the celery leaves when mature are rounded, 
brownish, and usually quite distinct in outline. In severe cases, 
as the leaves become older and the spots more numerous, the 
tissue between the spots breaks down and the entire leaf may 
wither. Pycnidia may, however, appear while the spot is still 
quite or entirely green. In this respect S. A pii is widely removed 
from those species in which the pycnidia ripen after the develop- 
ment of a well-marked discolored area. The mycelium of the 
fungus is at first intercellular and may spread at least from one 
to two millimeters through the tissue before the cells of the host 
break down. This stage is reached after from ten to fifteen days, 
depending on the temperature, the condition of the host, and 
perhaps other factors. The collapse of the mesophyll and palisade. 
cells is quite complete and leaves little more than the epidermal 
