104 Wisconsin Academy of Sciences, Arts, and Letters. 
It is plain from the above table that in the latitude of Mad¬ 
ison and with a period of three months, during which the tem¬ 
perature scarcely rises above the freezing point viable uredo- 
spores may be obtained at practically any time during the win¬ 
ter. As noted also, the spores were taken from very exposed 
situations. In each case about 10 °/o of spores germinated. The 
cultures made after January 1st did not vary greatly in this 
respect excepting in the case of the oat rust spores collected 
January 26th. Of these spores 60% germinated. In all cases 
the germ tubes were healthy in appearance and reached a nor¬ 
mal development. The time required for germination varied 
from three to six hours. 
In order to make permanent preparations showing the per 
cent of spores which germinate and the length and appearance 
of the germ tube, the following method was devised. On one 
side of a clean slide a thin him of albumen lixative, prepared by 
mixing equal parts of egg albumen and glycerine, is applied. 
On a slide so prepared is placed a drop of distilled water con¬ 
taining the spores. When germination has occurred, the water 
is allowed to evaporate until the slide is nearly dry and the slide 
is then immersed in a killing solution. I have found Flem¬ 
ming’s weak solution very satisfactory. Thirty minutes is 
usually sufficient time for the exposure. After killing, wash 
with water and harden by carrying the preparation through the 
different grades of alcohol, as follows: 
30% . 3 minutes. 
50% . 5 minutes. 
70% . 5 minutes. 
80% . 5 minutes. 
95% ... 5 minutes. 
100% . 1 minute. 
The slides may then be bleached or stained at once. Short ex¬ 
posures to the stains are most satisfactory. I have used Flem¬ 
ming’s triple stain exposing to the Saffranine three-fourths of a 
minute; Gentian violet', two minutes, and using the shortest 
possible exposure to the saturated solution of Orange G., or 
using that solution diluted with three times its volume of water. 
Mayer’s haematoxylin brings out the nuclei perhaps even more 
clearly. This stain was prepared by mixing a solution of 0.1 
