ON THE DEVELOPMENT OF LICHENOPORA VERRUCARIA. 111 
it is quite possible that the phenomenon is not very uncommon. 
After the commencement of embryonic fission, at any rate, it 
would be quite impossible to say whether one embryo or two 
were originally present. It will be remembered that two eggs 
are sometimes borne by a single polypide (fig. 16). It may 
fairly be inferred that under certain circumstances both eggs 
may develop. 
Some idea of the general appearance of the embryo at 
Stage C may be obtained by the inspection of figs. 23, 24, but 
it is often by no means easy to make out the structure of the 
embryo, or indeed to be sure how many nuclei belong to it, and 
how many may have been derived from intrusive follicle-cells. 
I have previously pointed out (6, p. 215) that the follicle- 
cells in Crisia do push their way in among the blastomeres ; 
and I have obtained a good many preparations of Lichenopora 
in which this process appears to be taking place. I can say 
no more with regard to the structure of the embryo than that 
it is a mass of protoplasm containing nuclei; and I am unable 
to say whether, at this stage or even later, these nuclei are 
arranged with any relation to embryonic layers. 
Whatever doubt may exist with regard to the exact details 
in Stages A and B, there cannot be the slightest doubt that the 
“suspensor stage ” is a perfectly normal phase of the develop- 
ment. I have examined some thirty-eight colonies in which 
the suspensor was present in the condition described above. 
With hardly any exception, I have found this stage in colonies 
which measure ‘40—'68 mm. in length (in sections) and ‘30— 
*55 mm.in breadth. The fertile zoeecium may or may not have 
a testis, and I cannot lay down any general rule on the subject. 
In two or three observed cases more than one zocecium was 
fertile. The only other variation which need be recorded, 
although it might equally well have been considered under the 
next stage, is the occasional occurrence of a young polypide bud 
in a zocecium which has reached the normal suspensor stage, 
and has recently lost its polypide by degeneration. 
In some cases this bud appears simultaneously with the 
development, in other zocecia, of buds which are clearly formed 
