Gymnosporangium. 233 
are slightly smaller than those of G. clavarieforme, and the cells of the 
pseudoperidia are delicately reticulated and longitudinally wrinkled. 
In thirty-six cultures I have produced the ecidiospores on C. oxyacan- 
tha from G. confusum ; in six cultures on Pyrus vulgaris (quince), and 
in seven on Mespilus germanica (medlar). I have failed to produce 
any result on apple in three experiments, and on beam inone. Ofthese 
cultures several were serial. Thus, on May 16, 1887, three pears 
and one thorn were infected from the same material ; on the three pears 
no result was obtained, but on the thorn zecidiospores were produced. 
In another series, on the same day, a pear, a quince, and a thorn were 
infected ; the quince and thorn had spermogonia on the 3oth, but 
no result was obtained on the pear. Again, on June 16, a quince, 
two pears, a thorn, a beam, and an apple were infected ; the quince 
and thorn became infected with the ecidiospores, but the pears, 
apple, and beam remained free. On April 25, a pear and two thorns 
were infected ; the two thorns produced the ecidiospores (spermogonia 
appearing on one on May 5, and on the other on the roth), but the pear 
remained free. On May 7, 1885, the same infecting material was 
applied to a medlar and six thorns; both the medlar and all the 
thorns became affected by the 2oth with the spermogonia. In due 
time on the thorns the zcidiospores were developed, and these were 
on June 25 applied to a healthy sabine bush. In September, it was 
noted that many of the leaves had turned yellow ; these during the 
winter and following summer (1886), fell off, and in March, 1887, the 
G. confusum appeared on those parts of the branches from which the 
leaves had fallen off. It may be added, that in only one duplicated 
culture out of the hundred I have made in elucidating the life-history 
of the sabine Gymnosporangia have ecidiospores on both thorn and 
pear been produced from the same infecting material, This was 
doubtless caused by an accidental mixture of teleutospores. 
Gymnosporangium clavarizeforme. (Jacq.) 
Ai cidiospores —Pseudoperidia on yellow, thickened spots, at first 
flask-shaped, then cylindrical, light brown, at length becoming 
fimbriate above. Spores subglobose, verrucose, pale brown, 
20-40 X 20-28, 
Teleutospores—Mycelium perennial, causing fusiform swellings on 
the branches. Spore-masses ligulate, compressed, sometimes 
bifid, at first firm and cartilaginous, becoming gelatinous, pale 
orange, about 10 mm. long. Spores fusiform, constricted, 
dark yellow, 7o-120 X 14—-20p. 
