96 Disease of Fruit Blossom 



The cells are mostly single or in pairs, seldom in long chains. No 

 endospores have been observed in any cultures. Involution forms are 

 produced very readily, especially at temperatures of 25-30° C, and in 

 old cultures. These involution forms attain often a length of about 

 100 f^ and are irregularly swollen. The optimum temperature for growth 

 is about 18° C. 



In bouillon at 15-18° C. a slight cloudiness is formed in 24 hours, 

 and a good growth obtained after two days ; after four days there is 

 an appreciable deposit and a slight thin film on the surface of the liquid. 

 At 25° C. growth is a little slower, and at this temperature after 48 hours 

 the cells gradually increase in size and begin to lose their motility. 

 Small chains and involution forms are then soon developed, and after 

 four to six days the organism has completely changed its original form. 

 It grows out into long threads and large, irregularly swollen and often 

 very granulated forms. Movement is then practically stopped. 



At a temperature of 18° C. the cells do not change their form or lose 

 their motility until the cultures are getting old. 



If involution forms from a six-day old culture are placed in fresh 

 bouillon and kept at a lower temperature, the new cells quickly begin 

 to assume the normal size and motility. 



In two months old bouillon cultures, the cells collect at the bottom 

 of the vessel, forming a disc of somewhat gelatinous character, and the 

 liquid is left perfectly clear. 



With bouillon gelatine stab cultures show feeble development after 

 24 hours. After 48 hours there is good growth with crateriform lique- 

 faction ; after six days the liquefaction is stratiform, and after eight 

 days all the gelatine is liquefied and a fiocculent deposit formed. Streak 

 'cultures after 48 hours show strong liquefaction, there being a broad 

 concavity in the gelatine and a cloudy liquid and white, fiocculent 

 deposit in the tube. 



In plate cultures of gelatine media colonies are extremely character- 

 istic after four days. The submerged colonies are small and white, 

 the surface colonies are liquid with smooth edges, round, 6-8 mm. in 

 diameter, concave, moist and glistening, semi-transparent, often with 

 small white nuclei in the centre and concentric rings of granular matter 

 beyond, and with whitish margins. Under the microscope the surface 

 colonies show a fiocculent deposit and a margin forming a double 

 ring. 



The liquefying action is very pronounced ; and in a plate culture 

 the whole gelatine is generally liquehed in about eight days, even if 



