TAXONOMIC CHARACTERS OF ALTERNARIA AND MACROSPORIUM 455 
surrounding the punctures. Unless otherwise stated, successful inoc- 
ulations also occurred on the unbroken leaf surface. To check the 
results of the needle-prick inoculations, sterile needle pricks were 
always made and all the plants kept under identical conditions. In 
no case did the control plants show signs of fungous invasion around 
the needle pricks. They will receive no further mention. Unless 
otherwise stated, spores of the fungus used were always re-isolated 
from the spots caused by the inoculations. In the following discussion 
the terms "normal" and "characteristic" indicate that the spot or 
fungus appeared the same as in the cases of natural infection. 
AUernaria solani from potato leaves: Inoculations were made from 
the first and tenth generations on agar and from spores taken directly 
from potato leaf spots. The mycelium was used as the inoculum, 
since very few spores were produced in culture. All of the inoculations 
with mycelium were made by needle pricks on plants under bell jars. 
The plants inoculated were: potato {Solanum tuberosum); Datura 
stramonium; tomato (Lycopersicum esculentum [L.] Mill.) leaves and 
fruit; Solanum nigrum L.; cabbage {Brassicae oleracea L.); iris (Iris 
germanica L.) ; Lactuca canadensis L. 
All inoculations on solanaceous hosts were successful; about 50 
percent of the inoculations on cabbage leaves failed; none succeeded 
on iris or Lactuca. The development of the spots was less rapid on 
Datura than on any other of the solanaceous hosts. Spots were all 
of the characteristic "target board" type. Very few spores were 
produced on any of the spots — none on the cabbage leaf. 
A. solani from Datura leaves: Inoculations by needle pricks and 
on the uninjured leaf surface were made with spores taken directly from 
leaf spots and with spores of the first and tenth generations from agar 
plates. All plants were kept under bell jars. The same plants were 
used as in inoculations with the strain from potato, and the results 
were similar except that all attempted inoculations on cabbage failed. 
The fungus developed least vigorously on potato leaves. On the other 
solanaceous hosts the spots were not different from those caused by 
A. solani from potato. Very few spores were produced on any of the 
spots. 
A. brassicae var. nigrescens from cantaloupe leaves: Inoculations 
were made with small pieces of diseased tissue, also with spores from 
the first, sixth and tenth generations on agar, by means of needle pricks 
and on the uninjured leaf surface. The plants were kept under bell 
