366 BOTANICAL GAZETTE [MAY 
The important thing is to get the tops of the plants covered with a perfect coating 
of the sulfur dust before the rust appears; the first application should be made 
as soon as the tops have made some little growth, say about three weeks after 
cutting stops, and a second and perhaps a third application should follow at inter- 
vals of about one month each. In some cases it may prove advisable to spray 
the plants first with some soap spray, to be followed by the sulfur dust to insure 
the sulfur adhering to the plants. If the best grade of flowers of sulfur be employed, 
it may be possible to cover an acre with about fifty cents worth. SmirH insists 
also upon the supreme importance of destroying all wild asparagus plants near 
the regular fields, since on these the rust first appears, and from them the field 
soon becomes infested.—E. MEAD WItcox. 
Germination in myxomycetes.—In a preliminary paper on the germination 
of the gia of myxomycetes, JAHN recognizes two distinct types of germination.?° 
The first type is represented by a single species of Ceratiomyxa, whose spore 
contains four nuclei, the spore content escaping as an amoeba which immediately 
ivides into eight swarmspores. In the second type, embracing all other myxo- 
mycetes, the spores are uninucleate and produce a single swarmspore. Regarding 
the conditions of germination, the following observations are made. The amoeba 
escapes by rupturing the spore-membrane by osmotic pressure, and if this is 
increased germination is prevented. The spores of Stemonitis do not germinate 
when placed in water, but if after being soaked they are allowed to dry they will 
germinate readily in water, an observation formerly made by LisTER. JAHN 
concludes that such spores contain a latent enzyme which is made active by the 
process of moistening and drying. Since maltose but not other sugars causes 
germination, this assumption is strengthened, as maltose is the decomposition 
product produced from glycogen stored in the spores—H. HASSELBRING. 
Blight canker.—WueETzEL has. published the results of his study of a canker 
of apple trees in New York state?® due to the same organism, Bacillus amylo- 
vorus, that is responsible for the well-known fire blight of apples and pears. This 
canker has been known in a general way for some years, but this seems to be the 
first demonstration, by the usual inoculation experiments, of the bacterial nature 
of the disease. Infection seems to take place only through wounds, and these 
may be due to pruning, to accidental wounding or ‘“‘barking” of the tree, or to 
the work of insects. The germ also enters at times through “water sprouts,” 
since cankers are often seen to appear about the base of such blighted shoots. 
Pear trees known to be affected with the blight should not be allowed to remain 
in the neighborhood of an apple orchard, and great care chould be taken to prevent 
the dissemination of the germs on the pruning instruments. Some variation 
in resistance to the canker was noted—E. Mrap Witcox. 
27 JAHN, E., Myxomycetenstudien. Ber. Deutsch. Bot. Gesells. 23:489-497- 1906, 
28 WHETZEL, H. H., The scat canker of apple trees. Bull. Cornell Exp. Sta. 
236:99-138. figs. 51-84. 1 
