ted products of waste. There is no
possibility that sperm and ova can escape by these tubes not in
company with coelomic fluid. In the case of many Oligochaeta where
there is no vascular network surrounding the nephridium, this function
must be the chief one of those glands, the more elaborate process of
excretion taking place in the case of nephridia surrounded by a rich
plexus of blood capillaries. A consideration of the mode of
development and appearance of the coelomoducts that have thus far been
enumerated (with the possible exception of those of the leeches) seems
to show that there is a distinct though varying relation between them
and the nephridia. It has been shown that in _Tubifex_, and some other
aquatic Oligochaeta, the genital segments are at first provided with
nephridia, and that these disappear on the appearance of the
generative ducts, which are coelomoducts. In _Lumbricus_ the connexion
is a little closer; the funnel of the nephridium, in the segments in
which the funnels of the gonad ducts are to be developed, persists and
is continuous with the gonad duct funnels on their first appearance.
In the development of the Acanthodrilid earthworm _Octochaetus_ (F.E.
Beddard) the funnels of the pronephridia disappear except in the
genital segments, where they seem to be actually converted into the
genital funnels. At the least there is no doubt that the genital
funnels are developed precisely where the nephridial funnels formerly
existed. If the genital funnels are not wholly or partly formed out of
the nephridial funnels they have replaced them. In the genital
segments of _Eudrilus_ the nephridia are present, but the funnels have
not been found though they are obvious in other segments. Here also
the genital funnels have either replaced or been formed out of
nephridial funnels. In _Haplotaxis heterogyne_ (W.B. Benham) the
sperm ducts are hardly to be distinguished from nephridia; they are
sinuous tubes with an intra-cellular duct. But the funnel is large and
thus differs from the funnels of the nephridia in adjoining segments.
Here again the nephridial funnel seems to have been converted into or
certainly replaced by a secondarily developed funnel. This example is
similar to cases among the Polychaeta where a true nephridium is
provided with a large funnel, coelomostome, according to the
nomenclature of Lankester. The whole organ, having, a