70 BULLETIN OF THE 
The attachment of the owcium to the body wall of the mother stock 
always remains small, as in Figure 99, and the embryo, in my experi- 
ence, does not come in contact with it. 
The formation of the first polypide in Oristatella is preceded by 
another process. Just as in the adult colony the inner layer of the 
polypide does not arise by invagination of the ectoderm, but from the 
stolonic cells lying at the base of the ectoderm (see Davenport, ’90, 
pp- 108, 109, Figs. 4 and 15), so too in the embryo. The first process 
then must be the formation of the stolonic cells. Figure 101 shows at 
the point marked sto. (which is at the pole of the embryo whence the 
inner-layer cells originated) that certain of the cells of the ectoderm ap- 
pear to be arching over a disk, containing about six cells in section, and 
thus coming in contact with the cylinder of cells (*) which projects 
from the neck of the occium. By a continuation of this process, the 
central disk of cells gradually comes to lie below the general level 
of the ectoderm, and to be cut off from contact with the neck of the 
ooecium (Fig. 97, sto.). The position of the stolonic mass with refer- 
ence to the neck of the polypide in this last figure must be considered 
abnormal ; it is at any rate exceptional, as it lies at one side of the neck 
of the ocecium, which does not, therefore, appear in this section. The 
next later stage which I have found is shown in Figure 102. The sto“ 
lonic mass seen lying beneath the ectoderm in Figure 97 has here 
already given rise to a young polypide (%., ex.), and its area is increas- 
ing in all directions by cell division (sto.). The beginning of a sec- 
ond polypide is indicated on the right at sto. The ectoderm is seen 
lying above this stolonic mass, and closely applied to the neck of the 
oocium (*). 
Neither at this nor at any subsequent stage have I been able to 
detect in Cristatella any “gürtelformige Placenta” such as exists in 
Plumatella. I am therefore of opinion that the process of nutrition, 
which is effected in Plumatella from the ocecium through its placenta, 
is effected in the Cristatella larva by its attachment to the neck of the 
oocium. I am pleased to see that Jullien (’90, pp. 13, 14) has also 
reached this conclusion in a paper which he has had the kindness to send 
me. At a later stage, the embryo, or young colony, seems to become 
detached from its intimate association with the neck of the oœcium, as 
we see in Figures 95 and 103. 
Figure 103 represents a stage in which there are two well developed 
buds, both shown in the section. There is, in addition, on another section, 
one less developed. The stolon is seen passing oralward of these twe 
