18 MICROSCOPIC PLANTS. _ [CHAP 
placed fragments of the leaves on which they had 
developed their secondary spores on young, but full- 
grown, Berberry leaves, under the same atmospheric 
conditions. In from twenty-four to forty-eight hours 
a quantity of the germinating threads had bored 
through the walls and penetrated amongst the sub- 
jacent cells. This took place both on the upper and 
under surface of the leaves. Since, in former experi- 
ments, it appeared that the spores would penetrate 
only in those cases where the plant was adapted to 
develop the parasite, the connection between P. 
graminis and cid. berberidis seemed more than 
ever probable. In about ten days the spermogonia 
appeared. After a time the cut leaves began to 
decay, so that the fungus never got beyond the 
spermogonial stage. Some three-year-old seedlings 
were then taken, and the germinating resting spores 
applied as before. The plants were kept under a 
bell glass from twenty-four to forty-eight hours, and 
then exposed to the air, like other plants. From the 
sixth to the tenth day, yellow spots appeared, with 
single spermogonia; from the ninth to the twelfth, 
spermogonia appeared in numbers on either surface ; 
and a few days later, on the under surface of the 
leaves, the cylindrical sporangia of the Actdium made 
theit appearance, exactly as in the normally de- 
veloped parasites, except that they were longer from 
being protected from external agents. . . . It seems, 
then, indubitable so far that “Acidium berberidis does 
spring from the spores of Puccinia gramints.” 
Other experiments have been made in which the 
spores of &cidium have been placed on healthy 
