288 BACTERIA IN RELATION TO PLANT DISEASES. 
The organism occurs singly, in pairs, and more rarely in fours joined end toend. Long 
chains and filaments have not been observed. Pseudozoogloez or flocculent particles do 
not occur quickly in bouillon, but compacted masses have been observed on plates, etc., and 
they occur in the plant. Usually in fluid cultures no rim or pellicle is formed, but there may 
be flocculence in some liquids, e. g., Uschinsky’s solution, though 
this is often wanting. Spores are not known to occur. This organ- 
ism is a white, wet-shining, schizomycete, motile by means of 4 to 8 
peritrichiate flagella (fig. 84). In young cultures motility is easy 
to observe. It has also been observed in slime taken directly from 
the vessels of the cucumber, melon, etc., and diluted with sterile 
water. In the plant motility is easier to observe in rods taken from 
tissues recently invaded than in those taken from crowded vessels. 
Involution forms occur in the plant and in various media—beet-juice, 
cucumber-juice, peptone-water, potato broth (vol. I, fig. 21), etc. 
On steamed potato the growth is white and so closely like the 
substratum in color that it is scarcely to be distinguished therefrom 
except by its smooth, moist, glistening appearance. It has very little action on potato- 
starch, even very old potato-cultures reacting strongly with iodine. It does not soften the 
middle lamella of potato-cells. Potato-cylinders may or may not be grayed. In one experi- 
ment the organism remained alive on 
potato over seven months (16° to 18° a of eo@me @e @Sap 
C.), but usually it is dead much sooner. Fig. 83.f 
In one set of experiments no 
growth was obtained on red turnip-rooted table-beets, nor on turnip-roots, radish-roots, 
or cauliflower-petioles. When these experiments were repeated some years later the fol- 
lowing results were obtained: On the beets growth was delayed but finally appeared. It 
was visible in one tube on the sixth day, in another 
on the fifteenth day, and in a third on the twenty- 
second day; the fourth tube remained sterile. Similar 
results were obtained by a repetition of the experi- 
a ment: There was marked retardation of growth as 
compared with that in the agar-stab, none being 
visible on the beets the fourth day; on the thirteenth 
; day there was a visible growth in one of the tubes but 
, not in the other, on the twentieth day a typical 
growth appeared in the second tube. Upon radishes 
ree mm. divided into e's. 
| similar results were obtained, viz., marked retarda- 
vos MM. tion but final growth in most of the tubes. No 
growth was obtained on turnips (two sets) and only 
Fig. 84.t a doubtful growth on cauliflowers. 
In 1896, inoculations were made into the juice 
of red table-beets filtered sterile and used both with and without the addition of calcium 
*Fic. 82.—Bacteria from interior of cucumber-stem at time of general wilt of foliage, but while main axis was still 
green and normal in appearance (plate 1, fig. 2); bacteria were present in vessels in enormous quantities. The great 
mass of them were of size and shape of 2, those of size 1 being seen only occasionally. Drawn unstained with Abbe 
camera, Zeiss 3 mm. 1.40 n. a. apochromatic objective, and No. 18 compensating ocular. Anacostia, D.C., July 15,1893. 
{Fic. 83.—Free-hand drawings of paired rods of B. tracheiphilus which have lost their flagella. Stained by van 
Ermengem’s nitrate of silver method in April, 1895,and measured after lying in balsam until Oct., 1895. Size of organ- 
ism appears greater when stained in this manner than when stained without flagella-mordants. Very careful measure- 
ments of one member of each paif-gave following result in microns: 2.03 X1.05; 2.10 X0.98; 2.55 X1.10; 2.18 X1.05; 
2.75 X1.20; average 2.32 X1.08. Circa X1500. 
tFic. 84.—Camera drawing from cover-glass preparation of young culture of B. tracheiphilus stained by van 
Ermengem’s nitrate of silver method. Flagella distinct; hundreds on cover-glass. Some rods with only one or two 
left, others with as many as 8; most bear about 6. An occasional flagellum is 10.5 u long; most are shorter. Oct. 4, 
‘1895. Circa X 1500. 
