ON THE DEVELOPMENT OF LIOHENOPORA VERRUCARIA. 97 
L. verrucaria the brown bodies formed by the degeneration 
of the polypides are absorbed from time to time, so that a 
zocecium hardly ever contains more than one or at most two 
brown bodies, those of L. hispida (again judging from my 
single series of sections) accumulate at the basal end of the 
zocecium, a considerable part of which is tightly packed by a 
mass of brown bodies. 
It seems clear that considerable differences in detail occur in 
the embryonic development of different Cyclostomes; but I 
believe that it will be found that the phenomena are funda- 
mentally the same throughout the group. 
Whatever may be the character of the arrangement by which 
the embryos are directly nourished, there can be no doubt that 
it is the polypides which ultimately supply the material at the 
expense of which they grow. In a very large proportion of 
the cases in which no embryo could be discovered, the poly- 
pides were not functional in all or some of the zowcia. A 
similar result is obtained by the examination of the degenera- 
tion of the embryo in fertile colonies. Leaving out of account 
doubtful cases, I have fifteen colonies in which degeneration of 
the embryo has clearly occurred. In eleven of these cases all 
the polypides of the colony had degenerated, this being pro- 
bably the proximate cause of the degeneration of the embryo. 
In some cases new polypide buds were being developed, and 
the colony would obviously have survived, and would probably 
have developed a new embryo from one of the younger poly- 
pides. One of the other four cases probably points in the 
same direction. The fertile zocecium contains two brown 
bodies, a polypide, and an embryo which commenced to dege- 
nerate in the ‘ suspensor stage ” (cf. fig. 24, a normal embryo 
at this stage), The remains of the embryo are between the 
two brown bodies, and it is highly probable that the distal 
brown body represents the polypide which originally supported 
the suspensor. The abnormal degeneration of this polypide, 
at an earlier period, probably resulted in the degeneration of 
the embryo, which is still just recognisable, although a new 
polypide has grown up in the fertile zocecium. 
VOL. 39, PART 1.—NEW SER. G 
