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F. D. HEALD AND R. A. STUDHALTER 
fence adjacent to traps 53 and 54 was also tested for spore expulsion 
with positive results. These results give added emphasis to the 
statement already made (7) that the chestnut blight fungus has a 
most remarkable power of ascospore production. 
Discussion 
A comparison of the results obtained at the two stations shows a 
very general agreement in the more important features. All of the 
traps at West Chester were set on native coppice while those at Martic 
Forge were on Paragon trees grafted on native coppice. Some of the 
traps at the latter station were set below the graft unions. The greater 
activity of the perithecia during the second season at Martic Forge 
as compared with the results at West Chester is probably due to the 
host relation, permitting a somewhat more rapid maturing of the 
fungus at the latter place. 
Since the prolonged perithecial activity established by our obser- 
vations for Endothia parasitica, is not in accord with what is known 
in regard to many other pyrenomycetous fungi, an explanation for 
this peculiarity should be sought. There seem to be two important 
features in the development of the fungus that contribute to prolonged 
perithecial activity. First, the period of successive maturing of asci 
is very extended. This fact is substantiated by the work of Heald 
and Walton (7) on the expulsion of ascospores under laboratory condi- 
tions, and is in agreement with the study by Anderson (9) of the 
morphology of the perithecia. The second feature not so clearly 
revealed by the morphological studies (9) appears to be the successive 
maturity of the perithecia in a given stroma. All perithecia in a 
given stroma do not reach maturity at the same time, some being still 
buried deep in the stromata when the necks of others adjacent have 
reached the surface and are in a condition to expel spores. Add to 
the above features the fact that there is no seasonal relation to the 
maturing of perithecia and one must admit that Endothia parasitica 
is remarkably well equipped for the continuous production of asco- 
spores. 
During the progress of our work detailed examinations were made 
of the perithecial pustules included under each trap, their condition 
being recorded at the beginning of the tests and at intervals there- 
after. As a result it can be definitely stated that the development of 
new stromata was the exception, the bulk of all expulsion recorded 
coming from stromata that were present at the beginning of the tests. 
