914 The American Naturalist. [November,. 
2. Morphology : 
(1) Shape, size, etc—The bacteria which Dr. Wakker regards. 
as the cause of this disease are represented on his Plate I, Figs. 
1-8 (34). They are two to four times as long as broad, with an | 
ordinary length of about 2.54. Their form is therefore more or 
less that of a cylinder, but with rounded ends. They are said 
to agree tolerably well in size and shape with Bacterium Termo. 
The organism was described as Bacterium Hyacinthi in 1883, but 
` was placed under Bacillus by Trevisan in 1889. When these 
bacteria have been in a nutrient liquid for some time a certain 
number become longer than they were, and now measure 4 x, 
while the ordinary length is only 2.5. Later on, as the nu- 
trient matters of the liquid are becoming exhausted, the bac- 
teria diminish in size more and more, and gather into motionless. 
groups, which often have circular outlines and which grow by 
the accession of new individuals, while the motile bacteria. 
become less and less numerous. Bacteria from the dry slime 
were found to be only about half the ordinary size, but on 
placing them in nutrient fluids they resumed their normal 
size. Examinations were made in hanging drops of nutrient 
fluid. 
(2) Capsule—No mention of any capsule. 
(3) Flagella.—No mention of flagella. The organism is said to 
be actively motile in culture fluids. Even those kept for some 
time in a dry state are said to have acquired motility on plac- 
ing them in nutrient fluids. In the yellow, viscid slime, as 
taken from the plant, they are not motile; but motility begins 
as soon as this is diluted with a ł per cent. salt solution, or 
with a suitable nutrient fluid. “After a short time all is life 
and motion ; the bacteria, in the form of straight but very flexi- 
ble rods, are to be seen moving about actively ; individuals in 
repose are rare. Among the undivided bacteria there are many 
which are in process of division, and which then show two 
individuals moving together; these, however, soon separate to 
continue an independent existence.” It will probably be found 
that the organism is also motile in the plant in early stages of 
the disease, i. e., before it has multiplied to such an extent as 
to fill the vessels. Dr. Wakker himself says : “ It is evident that 
