352 
ARTHUR DENDY. 
investing epithelium lias for its function the nutrition of the 
embryo, and that this is effected by the absorption of nutri- 
ment through the elongated necks of the ectodermal cells. 
Some of the ectodermal cells, however, exhibit no prolonga- 
tions of the neck, but are smoothly rounded off at the free 
end, and such cells may form a continuous layer over a con- 
siderable area. In most sections, however, owing to the 
forcible displacement of the nutrient epithelial cells and the 
rupture of the delicate connections between them and the 
ectodermal cells, the latter appear as if broken off at their 
outer ends, just outside the nucleus (figs. 19, 20, 22). 
The entire mass of the embryo within the ectodermal layer 
is made up of a clear, jelly-like matrix, in which immense 
numbers of large, amoeboid wandering cells are embedded 
(figs. 19, 22). These cells appear somewhat larger than the 
ectodermal cells, but I shall show presently that there is very 
strong reason to believe that they are simply ectodermal cells 
which have left their places in the outer layer, and, becoming 
amoeboid, wandered into the central jelly. Between the large 
amoeboid cells very delicate branching stellate cells may some- 
times be seen (fig. 22, st. c.). 
The amoeboid cells may put out pseudopodia in all directions, 
but often they appear to be radially elongated and more or less 
bipolar. I think my sections, and especially such as that 
represented in fig. 22, show conclusively that the amoeboid 
cells are derived from the ectodermal layer. They agree 
firstly in all essentials with the cells of the latter, and in those 
parts where the ectodermal cells, having the clearer, outer 
end of the neck evenly rounded off, present a characteristic 
feature, a precisely similar clear, rounded-off neck may often 
be seen in the amoeboid cells immediately beneath the ecto- 
derm. In fig. 22 two cells appear just leaving the ecto- 
dermal layer and becoming amoeboid by the emission of 
pseudopodia. The amoeboid cells are from the first highly 
granular and, at what I believe to be an early stage of the 
proceedings, each one has a spherical nucleus resembling that 
which occurs in the ectodermal cells. Sometimes the amoeboid 
