208 
Transactions of the Royal Society of South Africa. 
occasion, after prolonged observation, and when the fluid was almost dried 
lip, innumerable minute specks of bright light were plainly seen. These 
were well defined, each standing out distinctly on the dark background as a 
bright star-like glow. The glow of each particle did not, however, last for 
more than six to ten seconds, though some remained distinct for about thirty 
seconds. The light appeared first as a faint speck, and gradually reached 
its maximum as a steady glow, when it faded off rather suddenly. This 
appearance was not readily observed in this way, and often the light died 
down uniformly. Another method, however, by means of which the luminous 
particles could be readily distinguished was subsequently found, when it was 
accidentally discovered that the fluid so dried up could be again made 
luminescent by the application of water. If a quantity of water be put on 
the slide, it was noticed that, at the point where it came in contact with the 
dried substance, a distinct glow appeared, and this, when examined in the 
dark under the microscope, was seen to consist of numerous, discrete, lumi- 
nous particles. As the water encroached on the dried substance, an area of 
bright luminous specks, like a starry sky, passed slowly over the field of 
vision, at the point of contact of the water and dried substance. Sub- 
sequently it was found that the luminosity could also be renewed simply by 
breathing gently on the dried slide, but in this case it was of very short 
duration. The experiment was then tried of drying the slide rapidly, by 
subjecting it to a temperature of about 60° C, when the luminosity again 
reappeared on the application of moisture. 
It was, of course, impossible to locate the exact position of these luminous 
particles with reference to the cells in the fluid, which were invisible in the 
darkness, but by turning on an artificial light after their position in the field 
of vision had been noted, it was observed that they were situated in the 
cells, but that all of the cells were not luminous, or at least did not give 
out light sufficiently strong to be seen through the lenses of a microscope. 
It was only on one occasion, however, that three such isolated cells were 
observed to have these luminous particles, and then they were apparently in 
the process of breaking down. 
The luminous particles were found amongst the discharged granules of 
the cells in abundance. 
The size of the luminous particles could not be accurately ascertained, 
but they were of about the same size as the small particles already men- 
tioned as occurring in the cells, and there is good reason for believing that 
they were identical with them. Such solid particles are known to occur in 
the cells of the body cavity, and are believed to be the result of the trans- 
formation of the fluid spheres, which are purely excretory matter. Thus 
Kiikenthal and Joseph describe in Tubifex and Lumhriciis the large brown 
masses in the chloragogen cells as being transformed into small solid and 
dark particles. In the present case, however, these particles appear to be of 
