248 BOTANICAL GAZETTE [APRIL 
Pot 56. Four shoots (from a whole potato), 250, 240, 220, 100™™ high, with 
large leaves. 
ot 57. Four shoots (from a whole potato), 130, 160, 170, 1g0™™ high, with 
large leaves. 
In two days intumescences had begun to form on all the plants. In three 
days they were very numerous over all the plants. 
EXPERIMENT XX 
Five plants were placed in darkness, with an average temperature 
of 79° F. 
Pot 58. Four shoots (from a cut potato), 300, 250, 250, 270™™ high, with large 
eaves. 
Pot 59. Three shoots (from a cut potato), 280, 300, 290™™ high, with large 
eaves. 
Pot 60.. Three shoots (from a whole potato), 300, 250, 140™™ high, with large 
leaves. 
Pot 61. Three shoots (from a cut potato), 230, 130, 150™™ high, with large 
leaves. 
Pot 62. Three shoots (from a cut potato), 240, 220, 200™™ high, with large 
leaves. 
In five days none of the plants had developed intumescences, but they were 
very badly decayed from the excessive warmth and moisture. 
EXPERIMENT XXI 
At the same time some of the old plants, the second and third 
shoots from potatoes planted previously, were placed under bell jars. 
They all had rather small leaves and slender stems and were from 
200 to 300™™ high. Three were placed in the shade and three in the 
sunlight and all failed to produce intumescences. 
EXPERIMENT XXII 
A few shoots of potatoes were stimulated with the various copper 
salts used by Von ScHRENK (Q) in producing this disease on the 
cauliflower, to see if they would have a like effect upon the potato 
plant. The leaves of two shoots were stimulated with the following 
salts: copper ammonium carbonate, copper sulfate, copper acetate, 
copper nitrate, copper chlorid. 
At the same time two shoots of the old plants were stimulated 
with each of these salts. All of these plants were left uncovered. 
After twenty-four hours burnt patches appeared on all the shoots 
wherever the sprays struck. The entire tissue through the leaf to 
