KUNKEL: ORANGE RUSTS OF RUBUS 563 
acteristics which show that these spores in their germination 
function as aecidiospores. The appearance and behavior of the 
nuclei in the tubes is in striking contrast to what was observed in 
the study of the germination of the spores of Caeoma nitens (6, 7). 
The germination tests show that the aecidiospores brought 
from New Hampshire function in an entirely different way from 
those collected in the vicinity of New York City. An experiment 
was next performed for the purpose of determining whether they 
would infect wild blackberry plants growing in this region and 
whether or not they would give rise to the teleuto-stage of Gymno- 
conia interstitialis. A number of plants of Rubus villosus Ait. 
and Rubus argutus Link found growing wild in the Bronx, New 
York City, were transplanted to flower pots and placed in a green- 
house. After they had recovered somewhat from wilting due to 
the cutting of the larger roots, nine plants of Rubus villosus Ait. 
and three plants of Rubus argutus Link, were placed in a moist 
chamber after being dusted with aecidiospores brought from New 
Hampshire. : Unfortunately most of the spores had been used in 
the germination tests and only a limited quantity of the material 
was left for the infection work. An equal number of plants of 
each of the species used in this experiment were left uninoculated 
and served as checks. The plants were inoculated on the after- 
noon of July 1 and were left in a damp chamber for twenty-four 
hours. They were then placed in the open greenhouse beside the 
uninoculated plants. On August 15, all of the plants were care- 
fully observed. One plant of Rubus argutus Link, was found to 
bear sori of Puccinia Peckiana. Only four leaves were infected 
but each of these showed numerous sori. All of the other plants 
appeared quite healthy and showed no signs of infection. It is 
difficult to understand why more of the plants inoculated did not 
become infected, but Liro (9) and Fischer (5) both report similar 
experiences with Gymnoconia. The check plants were all quite 
free of rust. Since Puccinia Peckiana has never been found on 
the blackberry plants in the vicinity of New York City we must 
assume that the plants brought into the greenhouse from the Bronx 
were free from this rust and that the infection obtained was the 
result of sowing the aecidiospores of the New Hampshire Cacoma. 
This experiment confirms the results of Tranzschel (13), Clinton 
