126 SIDNEY F. HARMER. 
which the brown body can be got rid of except through the 
agency of a new polypide. In the fertile zocecium, on the 
contrary, the brown body passes upwards to the neighbourhood 
of the orifice (beginning of Stage D), and the basal end of 
the zocecium is left completely empty. In examining the base 
of colonies in the later stages of embryonic development, one 
of the oldest zocecia is usually found to be empty; and it may 
safely be inferred, in most cases, that this was the fertile 
zocecium. z! commonly possesses a functional polypide even 
during Stage G; and either z? or z3, as the case may be, is 
usually in the same condition. The other one of these two is, 
however, usually empty. In some cases the lower half of the 
fertile zocecium is seen to be cut off from the upper by a 
transverse septum, as described in Stage E (see p. 108). It is 
probable that this is the normal arrangement, and that the 
function of the septum is to restrict the embryos to that part 
of the fertile zocecium which is on a level with the rest of the 
ovicell. 
The active production of secondary embryos during this 
stage seems to have a well-marked effect on two sets of struc- 
tures in the rest of the colony; namely, on the testes and on 
the brown bodies. 
Colonies which are in the earlier stages (A—C) have testes 
in some of their zocecia in the great majority of cases. There 
can be no doubt that the colony of L. verrucaria is ordinarily 
hermaphrodite ; and, as we have seen, a testis may or may not 
be present, with the embryo, in the fertile zocecium. Prouho 
(18) has recorded some extremely interesting observations on 
the succession of the polypides in Alcyonidium duplex; 
in which a polypide which produces spermatozoa degenerates 
into the condition of a brown body, and is succeeded, as a 
normal part of the life-history, by a polypide which produces 
an ovary. It is quite possible that phenomena of an analogous 
nature may occur in Lichenopora, although the details are 
obviously different. If continuous observations of the zocecia 
of a young living colony could be made from day to day, it 
might be possible to show that the apparent irregularity in the 
