Holden and Harper—Nuclear Phenomena. 67 
Melampsora, Gymnosporangium,, Coleosporium, TJromyces, Ae- 
cidium and Phragmidimn has lead to the conclusion that Coleo¬ 
sporium sonchi-arvensis is exceptionally favorable for a more 
detailed study of the nuclear' phenomena. As. will be seen 
from the figures, the karyokinetic division is far less aberrant 
in type evert than might be expected from duel's figures. The 
material was for the most part collected during the summer and 
autumn of 1899. The material was fixed by placing it for 
twenty-four hours in Flemming's stronger solution. It was 
then washed in running water for four hours and hardened in 
alcohol in the usual manner. Where the material was to re¬ 
main some time before being imbedded, it was transferred 
through seventy per cent alcohol to a, mixture of equal parts of 
glycerin, alcohol and water 1 . It was later imbedded and sec¬ 
tioned in the ordinary manner. The sections were bleached on 
the slide for four hours in a three per cent solution of hydro¬ 
gen peroxide. The triple stain with safranin, gentian violet 
and orange was used almjost exclusively. The fungus was 
found on the host plants, Solidago Canadensis and ulmifolia > 
Aster sagittifolius and Callisteplus sp. There seems to be 
little or no difference in the rust from these different host 
plants. It was perhaps a little more vigorous on the Calliste- 
phus. On this plant only small patches of the leaves were af¬ 
fected, but the hvphae of the rust seemed to be a trifle larger. 
The first uredospores were found on July third, but then in 
such abundance that it was evident that they had been on the 
host plant for some time. The uredospore material was abun¬ 
dant. throughout the remainder of the summer and was found 
as late as the middle of November. Teleutospores were not 
abundant and were found only in the middle of the season. In 
autumn plants bearing uredospores were placed in the green¬ 
house. Here they continued to produce uredospores through¬ 
out the winter. But if left undisturbed the plants soon rid 
themselves of the rust by the natural dying off of the leaves in¬ 
fected by it. The rust, seemed unable to spread from one. leaf 
to another under the conditions in the greenhouse. The entire 
plant was. at times covered with a mildew, Erysiphe cichora- 
cearum. In the early part of the winter the rust was easily 
