66 A Baiterial Spot of (JItnis 



direct from the tissues of the host, and if a small portion of the viscid 

 mass oozing from affected areas on the fruit be mounted in water the 

 rods diffuse out and immediately become very active. 



It is extremely active in young cultures; an examination under 

 the low power of the microscope of 18 to 24 hour old colonies on 

 nutrient agar shows the outer part of each colony as a swirhng mass 

 of actively motile rods. In li(|uid media the bacillus retains its 

 activity for a considerable length of time; chains from the pellicle of 

 a 16 days old broth culture separated and immediately became very 

 active on being transferred to water. 



The motility of the organism can be very well studied in prepara- 

 tions made from a young agar culture and observed with the dark 

 ground illumination. The rods move forward with a steady sinuous 

 motion which is frequently interrupted by rapid oscillating movements. 



The fiagella stain quite readily; in the living state they may be 

 stained by Straus' method (i). The position of the fiagella can be well 

 made out, they are obviously peritrichous but are in too rapid motion 

 for any accurate estimate of their number. With Ellis' modification 

 of Loeffler's method very satisfactory preparations were obtained. 

 There are 5 to 10 long peritrichous fiagella : these are several times the 

 length of the rod, measuring roughly 8 to 12 /x. They are not distri- 

 buted evenly over the surface but frequently consist of one or two groups 

 of 3 to 5 which are crowded up towards the poles (Plate XII, c). 



Capsules. The viscidity of the substance oozing from diseased 

 tissues and the leathery or mucilaginous texture of many cultures on 

 solid media at once suggest the presence of a capsule. 



A capsule may almost always be detected and may be stained 

 either by one of the special capsule stains, by a dilute solution of fuchsin 

 or with carbol gentian violet. The viscid drops oozing from the fruit 

 consist of capsuled rods embedded in a tenuous shme which appears 

 granular when stained by MacConkey's method (Plate XIII, d). 



In an impression preparation of a young agar colony all the rods 

 were definitely capsuled (Plate XIII, c) and in the older parts of 

 the colony become crowded together into small tough masses which 

 are firmly embedded in the medium. In certain cases streak cultures 

 on agar take on a roughened or shagreen-hke appearance, and the 

 streak becomes leathery and can be torn in a strip from the surface 

 of the medium. Old streaks of raised, shining, more homogeneous 

 appearance are usually mucilaginous: the difference in textuie a])pears 

 to have some relation to the amount of water present in the medium. 



i 



