McKenney — On Jjumiiions Bacteria. 221 



in temperature. In those in Avhich temperature was gradually raised, 

 the luminescence at once appeared as soon as the culture had reached 

 15°. In those in which temperature was rapidly raised by plunging in 

 hot water, a temperature of 25° was obtained in 30 seconds, and with it 

 strong luminescence. 



The effect of changing from the optimum to a higher temperature was 

 next studied. Cultures from 26° were gradually (in 15-30 minutes) 

 raised to a temperature of 30°. Light continued with unabated bright- 

 ness until 29.8° or 30.1° was reached and then the cultures immediately 

 became dark. 



Luminous cultures from 26° were plunged into water of 70°. In from 

 1 to 1.25 minutes the cultures were at 45° and the light instantly disap- 

 peared. Some of the cultures were slowly (15 to 20 minutes), others 

 quickly (2 minutes) brought back to a temperature of 26°. Lumines- 

 cence did not begin, however, as soon as the optimum had been reached. 

 Usually it was from 10 to 12 hours after such treatment before the cul- 

 tures were again luminous. 



A number of experiments were also made in which old cultures that 

 had ceased to emit light, and young cultures which were not yet lumi- 

 nous, had their temperatures raised and lowered, both gradually and 

 rapidly. In no case, however, did any luminescence result, except in 

 the very young cultures, which emitted light at the time in which un- 

 treated control cultures were also luminescent. 



ACCOMMODATION. 



In the preceding experiments it was found that for a very short period 

 (1-2 minutes) it was possible to have luminescence as much as 15° above 

 the normal maximum temperature for light production. Accordingly it 

 seemed desirable to learn whether the bacteria would adapt themselves 

 to life at higher temperatures and emit light. From the tables it will 

 be observed that growth is possible for 9° above the normal maximal 

 point for luminescence. 



Normal fish bouillon (a) was then inoculated with Bacillus phosphores- 

 cens and placed at 35°. A good growth was soon noticed, but during two 

 days no light was observed. From these cultures fresh inoculations were 

 made into another lot {b) of media. A rapid growth occurred, but no 

 light was produced. After 24 hours growth, fresh inoculations were 

 made into a third lot (c) of media. In these cultures growth was luxur- 

 iant like the preceding, but no light appeared in 24 hours. Inoculations 

 were again made to a fourth lot {d) of media. Growth was good in these 

 cultures, but they still remained dark, and after 24 hours transfer was 

 made to a fifth lot (e) of media. In these cultures not only was the 

 growth good, but 12 hours after inoculation a weak light was observed. 

 A little while before this (2 hours) a weak light was also noted in the d 

 cultures, which were then 34 hours old. Transfers were successively 

 made from the e set of cultures to sixth set,/, and from /to a seventh 



