- 428 CONNECTICUT EXPERIMENT STATION REPORT, IQI2. 
ARTIFICIAL CULTURES. 
Source of Cultures, etc. We have had cultures of Endothia 
gyrosa under observation for more than a year, and of the 
variety parasitica for more than four years. These have been 
obtained from many different localities, and from both chest- 
nut and oak in each case. For example, we now have eighteen 
different cultures of the chestnut blight obtained from localities 
in Massachusetts, Connecticut, New York, Pennsylvania, and the 
‘District of Columbia; and besides these we have had others from 
time to time. We have five cultures of the blight originally 
obtained from three different species of oak, from two regions 
in Connecticut and one in Pennsylvania. Of E. gyrosa on chest- 
nut we have fifteen cultures from eight different regions in 
Pennsylvania, Virginia, Tennessee, and North Carolina, and one 
from Europe; and ten cultures from three species of oak from 
five different regions in the District of Columbia, Virginia, and 
North Carolina. : 
We have grown many hundreds of these cultures on a variety 
of media in test tubes and Petrie dishes, though for most pur- 
poses tubes of potato- or oat-juice agar have proved the most 
satisfactory. From this extended experience we have been able 
to judge accurately as to purity of the cultures, constancy of 
their cultural characteristics, and differences that distinguish the 
variety from the species. Ordinarily the conidial spores of each 
have regularly appeared in these cultures, but in varying degree. 
In no case has the asco-stage of either been produced. Its 
production has seemed more likely to occur in the case of 
Endothia gyrosa, since in some cultures the conidial fruiting 
stage appeared as rather large, distinct, elevated pustules; but 
these have never shown any signs of ascospore formation. We 
have made some attempts, by special media or treatment, to 
induce the asco-stage to appear in these pustules, but without 
success, : 
Endothia gyrosa versus var. parasitica. The following 
characteristic differences were noted in special test tube cultures 
made at the same time on potato-, Lima bean-, and oat-juice 
agar, from twenty-five sources of Endothia gyrosa and ten 
sources of var. parasitica. In general, it may be stated that the 
potato-juice agar favors spore production for both, while the 
