Jan. io, 1914 
Some Diseases of Pecans 
327 
PEDIGREED CULTURES 
Starting with a single ascospore and a single conidium from the same 
strain of the fungus, two series of com-meal-agar cultures were carried 
for five generations. Each generation was grown for three weeks before 
transfers were made for the next succeeding generation, and conditions 
of temperature and medium were made as uniform as possible throughout 
the 15 weeks of the test. Observations in every case were taken at three 
weeks. In the first strain ascospores were always used in making the 
transfers, while conidia alone were transferred in the second strain. 
Ascospore Strain.—Generation 1 had numerous black, carbonaceous, perithecial 
groups and no acervuli, though a moderate number of conidia were developed hypho- 
mycetously. 
In generation 2 the perithecia and acervuli occurred in about equal numbers. In 
many cases the black perithecial clusters were surrounded with acervuli which were 
exuding pink masses of spores. 
Generation 3 exhibited dense black masses of perithecia near the base of the slants 
and a considerable number of acervuli which were mostly toward the upper part. 
Generations 4 and 5 were similar to the last, except that the two forms were more 
uniformly scattered over the surface of the cultures. 
Conidial Strain.—Generation 1 had numerous acervuli with exuding pink spore 
masses, but no perithecia. 
Generations 2 and 3 had numerous perithecial groups and acervuli well scattered 
over the cultures, with neither form greatly in predominance. 
Generation 4 had numerous pink spore masses along the streak, and perithecial 
clusters in moderate numbers near the base of the slant. 
Generation 5 had both forms in about equal numbers and well scattered over the 
surface of the cultures. 
Further cultural studies carried out in the same way as the one described 
above have given essentially the same results—namely, that a strain 
producing both spore forms will continue to produce both ascospores 
and conidia even though one form alone is used in reproduction. Varia¬ 
tions have occurred from time to time, but these have occurred irregu¬ 
larly and without continuance. Strains of the fungus from single 
ascospores have sooner or later always given rise to both ascigerous and 
conidial forms. However, some conidial strains have been obtained from 
the host which, after two years in culture, still produce only the conidial 
form. It would thus appear that there are conidial strains of the fungus 
which have lost the power of developing the perfect stage or which at 
least have not met with the proper inciting conditions. 
Morphology and Taxonomy 
The perfect stage has been noted less frequently than the conidial stage, 
but nevertheless the perithecia have been occasionally found on both 
leaves and nuts. The first evidence of perithecial formation is seen in a 
plexus of pseudoparenchyma tissue made up of more or less isodiametric 
fungous cells developed in the decaying tissues beneath the epidermis. 
This finally develops into the mature perithecium which ruptures the 
