428 CONNECTICUT EXPERIMENT STATION REPORT, 1912. 

 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 



