212 Papers from the Department of Marine Biology. 



bacteria which can still phosphoresce when moistened will give rise to 

 no new colonies. 



The question may now be raised as to \vhether bacteria whose struc- 

 ture has been completely destroyed by grinding in the dry state will 

 phosphoresce on moistening. Oxidation can not take place so long as 

 water is absent. Experiment shows that they will not phosphoresce, 

 as the following procedure indicates: Luminous bacteria dried on 

 glass wool are powdered in a porcelain mortar and divided into two 

 equal parts, A and B. A was then ground in the porcelain mortar for 

 20 minutes with pure quartz sand ; B was thoroughly mixed in another 

 mortar with an equal volume of sand, previously ground for 20 minutes, 

 and exposed to the air during the time of grinding A. In this way the 

 effect of quartz powder or the possibility of absorbing moisture from 

 the air would be the same for the unground bacteria B or the ground 

 bacteria A. On moistening B with sterile sea-water, a good phosphor- 

 escence appeared, while the ground material gave no light with sea- 

 water. I have repeated the experiment with the same result and feel 

 that there are no possible sources of error. Microscopic examination 

 shows the sand to be ground to the size of the bacteria or smaller and 

 it is well known that even the smallest cells may be broken up by 

 grinding with sand. I find that the dried luminous organs of the fire- 

 fly likewise lose their power to phosphoresce if thoroughly ground with 

 sand. This result differs from that of McDermott (21), who finds that 

 firefly tissue can be frozen and ground in liquid air without losing its 

 power to phosphoresce. Both A and B were inoculated on agar 

 nutrient medium. The ground bacteria, A, gave rise to no luminous 

 colonies, while the unground bacteria, B, did develop several luminous 

 colonies further proof that the ground bacteria were wholly broken up 

 and destroyed. 



EFFECT OF LACK OF OXYGEN. 



Many observers have shown that if luminous bacteria are suspended 

 in sea-water and the oxygen removed the light disappears and again 

 returns when oxygen is readmitted. Will the light reappear if the 

 cells are in the meantime cytolyzed? I have made many attempts to 

 obtain extracts of cells broken up in absence of oxygen which would 

 give light if oxygen were readmitted. All these efforts have failed. 

 The result might have been anticipated by the work of MacFadyen (27), 

 who found that luminous bacteria subjected to the action of liquid air 

 did not phosphoresce at that low temperature, but did phosphoresce as 

 soon as warmed again; further, that if the cells w r ere broken up by 

 grinding at the temperature of liquid air, there was no phosphorescence 

 on rewarming. MacFadyen worked, however, in the presence of oxy- 

 gen and moisture, and we might suppose that a slow oxidation too 

 slow to produce light went on in the material broken up at low tem- 

 peratures with consequent exhaustion of the photogenic material. 



