312 W. WOODLAND. 
ring which I do not think has been definitely described before 
is the protoplasmic continuity existing between them. This 
protoplasmic continuity is shown in Pl. 18, figs. 8, 11, 12, 15, 
etc., in which the cells form a single series, the members of 
which are conspicuously joined together by long protoplasmic 
threads into a continuous circle. ‘These connections between 
the cells of the blastoporic ring are primarily and not secon- 
darily formed, since the ring originates by the outgrowth from 
each longitudinal strand of two chains of cells (i.e. the cells 
are already connected), one on each side, which extend round 
the archenteric invagination and meet in the median ventral 
plane of the larva the corresponding two of the opposite 
strand. Until one of these chains of cells has met its fellow 
of the opposite side its foremost cell often has the appearance 
of protruding in front of it a long pseudopodial process which 
perhaps acts as afeeler. Connections (though not elongated) 
between some of the adjacent cells situated in the longitu- 
dinal strands doubtless also exist, though it is not always 
easy to see them. 
Starting, then, from this disposition of the mesenchyme 
cells in the blastoccele, viz. a blastoporic ring attached at two 
points to two longitudinal strands (text-figs. 3 and 4), the 
young spicules first make their appearance at the centres of 
the two longitudinal strands of cells, and in the form of one 
or more spherical granules contained in one or more cells 
(Pl. 18, figs. 1—5, 8, 15). In HE. esculentus, as elsewhere, 
“the simplest form of spicule is a minute granule, generally 
more or less spherical” (Sollas, 18), and thorough agreement 
on my part with this general statement leads me to here 
protest against that prevalent dogma which, in my opinion, 
most unwarrantably asserts that in all cases the calcareous 
spicule first, or, at least, early in the development, assumes 
the shape of a tetrahedron. In E. esculentus there is not at 
any stage a trace of such a crystalline form of the young 
spicule, nor have I detected such either in the young spicules 
of Cucumariider, of A. digitatum (25), or of Sycon 
sponges (24). Semon (20) himself, who is the chief authority 
