ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 121 
of Lichenopora; and every primary embryo examined at 
this stage differs in these respects from every other primary 
embryo. 
The main fact is, however, the same. The embryo at this 
stage has ceased to be a coherent structure,and has resolved itself 
into a number of complicated lobes of embryonic tissue, some 
of which have actually become separate from their neighbeurs, 
and some are ready to become separate at a moment’s notice. 
Even now a differentiation of two kinds of embryonic cells 
is not necessarily apparent. In fig. 34 there is some indication 
of the occurrence of inner cells, which are probably destined 
to give rise to the inner layer of the secondary embryo. Other 
preparations do not show any such clear differentiation. 
The general features of this stage are very characteristic. 
The fertile brown body is invariably present, and it is situated 
near the upper end of the fertile zoecium. The embryophore 
is shaped something like the lower (closed) end of a test-tube, 
and it still hangs down freely into the body-cavity of the 
zocecium. ‘The embryo or its parts usually lie in spaces which 
probably appear in the surrounding cells of the embryophore, 
by a process of vacuolation of the protoplasm. The aperture 
of the ovicell is beginning to develop. 
The present is a convenient place to raise the question of 
the function of the suspensor. It might have been supposed 
that it was a tube carrying spermatozoa to the egg, if it had 
not been for the fact that the suspensor is formed after the 
development of the embryo has commenced. The time at which 
one would expect fertilisation to take place is the stage before 
the embryonic investments are completed, when the egg is 
hardly separated from the fluid of the body-cavity. At this 
time spermatozoa are commonly found in the neighbourhood of 
the egg or of the embryo in its early stages (cf. fig. 19). 
The function of the suspensor appears to me to be probably 
connected with the nutrition of theembryo. During Stages 
C and D the suspensor remains quiescent; but it probably 
contributes to the formation of the mass of protoplasm in which 
the secondary embryos are supported from Stage F onwards. 
