NOTES 
ON LUMINOUS BACTERIA 1 . — Many instances of light produc- 
tion occur in Nature amongst plants and animals. This luminosity is 
most strikingly exhibited by marine animals and by minute vegetable 
cells belonging to the group of the Bacteria. Light-production by 
living protoplasm is a process intimately bound up with the life of the 
organism, as in the case of the luminous Bacteria. The luminosity of 
mineral and other inert bodies is dependent on an extraneous light 
source. 
Amongst light-producing organisms our knowledge of the process 
is most exact in the case of the Bacteria. Their simple semicellular 
structure, and the fact that modern bacteriological methods enable 
us to isolate and study particular organisms, renders it somewhat 
more easy to study the conditions under which light-production can 
best occur. The observations which are embodied in this paper were 
made on luminous Bacteria. These organisms are to be found 
mainly in sea-water and on dead marine animals. They are widely 
distributed in this respect. We have obtained and studied the most 
important types. About twenty-five varieties have been described, 
but it is probable that some of these are very closely related, if not 
identical. A hitherto undescribed form has been isolated from sea- 
water in the course of investigations made by one of us at Plymouth. 
It belongs, like most of the other species, to the group of the Bacilli. 
The temperature-conditions as regards growth vary considerably, 
and range from zero to 37 0 C. 
The luminosity of the sea is mainly due to higher forms of marine 
life and not to Bacteria, at any rate in northern latitudes. On the 
other hand the phosphorescence of dead objects, such as fish, &c., 
is due to bacterial forms of life. 
We have not been able to confirm the statements that luminous 
1 Abstract of paper read before Section K of the British Association, Belfast, 
1902. 
[Annals of Botany, Vol. XVI. No. LXIV. December, 190a.] 
S S 
