The Ohio Naturalist. 
[Vol. IX, No. 7, 
5 J ° 
In an effort to secure more perithecia from this material a 
number of spots were cut from leaves that were dried and laid 
away at the time of collection. These spots were placed in 
water to soften and after a few hours a part of them was taken 
out, killed, imbedded, sectioned and stained. Upon one of these 
spots both perithecia and pycindia were found (Fig. 9) similar to 
those before discovered upon separate spots—a fact pointing to 
the probability that both fruiting bodies sprang from the same 
mycelium. A few of the leaf spots not imbedded were left in 
the water for several days and when again examined showed a 
vigorous growth of mycelium which was producing in abundance 
the chain-like spores of an Alternaria (Fig. 4). A number of 
other spots similarly treated gave like results. A more thorough 
investigation of the specimens labeled Macrosporium catalpae 
was now made by soaking some of the spots in water and then 
mounting them in glycerin. This revealed conidiophores and 
chain-like spores (Fig. 5) similar to those mentioned above, 
from which it appears that the fungus known as Macrosporium 
catalpae is a species of Alternaria. Furthermore, one of the 
spots from which sprang mycelium bearing spores of Alternaria 
showed among its conidiophores a perithicium as shown in 
figure 7. 
In July the writer received a supply of infested leaves from 
Mr. Erwin F. Smith, of the Bureau of Plant Industry, at Wash¬ 
ington, D. C., collected from catalpa trees in that vicinity. Upon 
the spots on these leaves a species of Alternaria was found 
flourishing and when they were removed from the leaves, placed 
in a moist watch-glass and covered with a small bell jar a vig¬ 
orous growth of mycelium sprang up producing an abundance of 
spores in chains. As far as it was possible to determine by 
comparison, these spores were in all respects similar to those 
developed in a similar manner from leaves collected at Columbus. 
From the spores developed from leaves collected at Washington 
an artificial culture was made from which a pure culture of the 
fungus was secured. In August three young catalpa trees with 
leaves representing all stages of development were thoroughly 
sprayed with sterilized water in which an abundance of the 
spores from this pure culture had been placed. These trees were 
growing in a small court with walls on four sides and were in a 
thrifty, vigorous condition. The spores were sprayed upon 
them in the evening of a day on which at about noon a heavy 
rain had fallen. The next day was warm and cloudy and the 
moisture sprayed upon the plants in the evening was still visible 
upon them at noon the following day. The conditions seemed 
to be exceptionally favorable for the development of the spores 
yet not a single spot appeared upon the leaves of any of the 
trees. Spores taken from the same source at the same time and 
placed upon an artificial medium grew nicely thus showing that 
