Christman—Wintering of Grain Busts. 105 
gm. of Haematein dissolved in 5cc. of 90% alcohol with a solu¬ 
tion prepared by dissolving 5 gm. of alum in 300cc. of water. 
Thirty minutes’ exposure to this stain followed by a very short 
exposure to the dilute Orange G., gave the most satisfactory 
stain tried. This method of fixation and staining has been em¬ 
ployed with good results in preparing slides of various kinds 
of germinating spores and also of various kinds of germinating 
pollen-grains. The albumen fixative seems to have no injurious 
effect in any case which was tried. 
It may be noted early in the winter that in the case of badly 
rusted grain, many of the leaves become spotted with pale areas. 
Sections showed that the tissue beneath these spots contained 
mycelium and undeveloped spores. In order to determine 
whether such spots developed further and became open pustules 
during the winter and also to determine whether the oat plants 
could be wintered over with some protection a clump of badly 
spotted oat plants was covered in the following way. A bank 
of earth six inches high, enclosing an area twenty by twenty-two 
inches, was built around a patch of oat plants and the whole 
covered with a pane of glass. Certain leaves were placed in 
such a position that they could be easily seen. From time to 
time during the winter, the snow was removed from the glass 
and a little warm water applied when the oat plants could be 
seen very clearly. 
The oat plants were enclosed as above described on November 
18th, and a number of the pale spots marked. On December 
20th, it was observed that the epidermis was ruptured and open 
pustules had been formed in certain of the marked spots. Many 
of the white spots were still apparent. On January 17th the 
snow was again removed. The pustules and spots were in much 
the same condition as on December 20tli. The oat plants were 
fresh and healthy except where in contact with the glass. On 
January 23rd the conditions under the glass remained un¬ 
changed. After this date the experiment was interrupted and 
no observations were made on these plants. It seems probable, 
however, that uredospores and mycelium of P. coronata are at 
least as resistant as the oat plants on which they grow. As is 
shown in the table, spores from oats were germinated as late as 
