26 Bacterial Disease of the Mango 



the first distinct evidence of liquefaction (colonies crateriform), was 

 noticed after 14 days, and liquefaction was complete in about 24 days. 



Nutrient gelatine stab. A number of stab cultures, made in + 15 

 nutrient gelatine in test tubes measuring 7 x 1" and incubated at 20° C, 

 showed the following characters. 



After 48 hours at 20°C, the needle track was just distinguishable; 

 a thin line of white growth extending to the bottom of the tube. Three 

 days later the growth in the deep parts of the gelatine was seen to 

 consist of very numerous and minute spherical colonies. On the surface 

 of the gelatine there was a colony about 4 mm. in diameter and rather 

 deep coloured. 



In nine days the surface growth had sunk in a little saucer of lique- 

 faction, and under this there was a hemisphere of liquefied, clouded 

 gelatine. Five days later the top of the liquefied portion was 1 cm. 

 in diameter ; the surface colony remained entire, floating on the liquefied 

 gelatine. Its centre was deep coloured, but it was lighter towards the 

 margin. The shape of the whole growth was napiform, 1-5 cm. wide 

 at the broadest point. There was a sediment at the bottom of the 

 liquefied portion. 



In twenty days from the time of inoculation the growth had extended 

 to the width of the tubes and the liquefaction to a depth of 2 cm. 

 (Plate XI, fig. c). The cloudy, liquefied portion continued to increase 

 in size, became infundibuliform in shape (Plate XI, fig. d), then extended 

 downwards and finally completely liquefied the gelatine. 



The colour of the surface growth was deep chrome (Plate III, 17 — 

 Y, b) and that of the sediment light orange yellow. The culture had 

 no distinctive odour. 



In tubes inoculated at 25°C. liquefaction commenced after six days 

 and reached the stage shown in fig. d in nine days. 



Nutrient gelatine streak. Streak cultures on nutrient gelatine 

 incubated at 20° C. form a line of growth about 5 mm. broad along 

 needle track in three days. It is smooth, shining and yellow, and 

 opalescent at the edges. In a short time liquefaction commences at 

 the bottom of the streak, making a groove in the gelatine, and as it 

 continues the melted gelatine runs to the bottom of the tube. 



Nutrient gelatine shake. Shake cultures in nutrient gelatine developed 

 very numerous, minute colonies near the surface of the gelatine becoming 

 less numerous towards the bottom of the tube ; they are evident after 

 three days. Liquefaction sets in on the sixth day, beginning at the sur- 

 face of the medium and working downwards until the whole is liquefied. 



