124 HISTORY AND CAUSE OF THE COCONUT BUD-EOT. 



clear oily liquid. Cultures were made into tubes of this material, 

 but ill none of them was there the sMghtest sign of clouding. 



Determination op Characteristics of the Organism by Physical Methods. 



Optimum temperature. — Cultures in beef bouillon (+15) were 

 placed in different temperatures and it was found that good clouding 

 resulted in 24 hours and heavy clouding in 48 hours at any tempera- 

 ture from 25° to 45° C. Surface films formed more quickly at the 

 liigher temperatures, and the bouillon showed an inclination toward 

 clearing sooner than at the lower temperatures. Cultures have 

 remained heavily clouded at 30° C. for one month; at 22° C. (room 

 temperature) for two months and more; at 39° C. for one month 

 and more. The pomt of most luxuriant growth appears to lie 

 between 30° and 35° C. 



Maximum temperature. — The maximum temperature is not laiown 

 Cultures kept at 46° C. for two weeks became heavily clouded "wdth a 

 good surface film and afterwards gradually thinned, as though 

 having passed their best growth. 



Minimuin temperature. — Cultures in beef bouillon (+15) were 

 kept at various temperatures ranging from 3° C. up to room tem- 

 perature. After one month cultures at 4° C. and below showed no 

 clouding. Cultures at 8.5° C. faded to cloud until after one month, 

 when one-third of the tubes became thinly clouded. Cultures at 

 10° C. clouded slowly and within a week were moderately well clouded. 

 Thermal death point. — Cultures in beef bouillon (+15) were 

 exposed for 10 minutes in water heated to various temperatures. 

 Cultures exposed to an average temperature of 54.9° C. (variation 

 from 54.4° to 55° C.) for 10 mmutes failed to grow. Cultures exposed 

 to an average temperature of 51.6° C. (variation from 51.4° to 

 51.8° C.) failed to cloud in 24 hours, but in 48 hours showed a retard- 

 ing of growth, though not inhibition. Cultures exposed to an average 

 of 51.° C. (the variation from 50.8° to 51.2° C.) were moderately 

 clouded in 24 hours. 



Another set of experiments was made and the culture in bouillon 

 clouded in 24 hours after an exposure of 10 minutes to an average of 

 54° C. (varying from 53.85° to 54.05° C). Cultures exposed to 

 53.35° C. (varying from 53.20° to 53.40° C.) clouded well in 24 hours 

 as did cultures exposed to 52.80° and 52° C. 



The experiment was repeated, and cultures exposed for 10 minutes 

 to an average of 54° C. (53.95° to 54° C.) clouded in 18 hours. Cul- 

 tures exposed to a temperature of 55° C. (54.85° to 55.15° C.) 

 became lightly clouded in 18 hours and well clouded in 24 hours. 

 Three of the six culture tubes exposed to a temperature of 56° C. 

 (56° to 56.10° C.) clouded in 24 hours, the three remaining tubes 



228 



