210 Transactions of the Royal Society of South Africa. 
site, and the presence in several cases of numerous " pseudonavicellae " 
seemed to indicate that this parasite was a gregarine. 
It was found, however, on making sections, that the cells undoubtedly 
proceeded from the body cavity by a comparatively large aperture on the 
floor of the buccal cavity ; posteriorly also, within or at the edge of the anus, 
a small aperture was found on the dorsal aspect leading into the body cavity. 
There could be little doubt on this point, for sections were made of a worm 
which had just discharged the luminous fluid from the mouth, and in the 
sections the remains of this fluid in the mouth cavity could be clearly 
followed through the aperture to the body cavity. The structure and nature 
of these openings will doubtless prove of interest, but we are not concerned 
with them here further than that they throw light on the origin of the 
luminous cells. 
It was expected that the coelomic fluid and its contained cells would be 
ejected by the dorsal pores, as was found to be the case in a species of Lum- 
bricus obtained from the same locality, when placed in a preservative. This, 
however, was not the case ; indeed, dorsal pores seem to very inconspicuous 
or absent in this species of Chilota, as none were seen. 
The luminous cells therefore originate from the body cavity, and are 
apparently either free chloragogen cells or amoebocytes, or, maybe, a mixture 
of these. 
Biological Significance of the Luminosity . 
So striking a feature as the production of light by an animal naturally 
suggests the likelihood of a specific purpose for which the light is produced. 
There is usually, however, a considerable difficulty in assigning to it any 
definite function with certainty, even in those animals with distinct and 
somewhat complicated organs for the production of light. Thus, for 
instance, while it has been maintained with a good deal of reason that the 
light produced by the fire-fly, certain fishes and Crustacea are secondary 
sexual characters, this has been disputed. Certain luminous organs are 
apparently for the attraction of the prey of the animal, for scaring off or 
misleading enemies ; but while the complexity and apparent purposefulness 
of the organs undoubtedly point to a definite function, the proof of this, 
founded on facts, is markedly wanting. If this be the case in the higher 
animals it is much more so in the lower. Luminous protozoa such as Nocti- 
luca, so well known, luminous bacteria, equally well known, have no obvious 
" use " for their luminosity. There is no difficulty in suggesting a plausible 
use for the luminosity in the earthworm. Thus, when this luminous worm 
was first found crawling about on the surface of the ground in the semi- 
darkness, the patches of luminous mucus, while so readily attracting atten- 
tion, apparently served the purpose of drawing off attack from the worm 
itself, as it actually did in the observed cases — a common enough expedient 
in some animals, which sacrifice a conspicuous organ by throwing it off from 
