1028 The American Naturalist. [ December, 
nature of the methods employed, the use of corrosive sublimate 
solution to shrink the cells!apart save at the outer surface, 
raises grave suspicion as to the real nature of this outer con- 
nection. 
Some observations upon living eggs of Lamellibranchs seem, 
however, to strengthen the position assumed by Hammar and 
to make it probable that the intercellular connection observed 
by him is, in some cases at least, really a living ectoplasma. 
It is well-known that eggs frequently present a clear outer 
protoplasm that forms a true ectosare over the more gran- 
ular, yolk bearing interior part. In the eggs of the Lamelli- 
branch, Nucula delphinodonta, this is very marked. Here the 
ectosarc rises up into waves and also into blunt pseudopodia- 
like papille, as seen under oc. 8. obj. 4mm. These waves and 
processes change shape in such a way as to leave no doubt of 
the living nature of this ectosare. In one ease the ectosare 
extended all over the polar body, so that it was included as a 
bubble might be escaping through a film of jelly, and a clear 
stalk or base of ectosare was left between the egg and the 
polar body. But as these eggs were probably never fertilized 
and did not develop, the above phenomena may well have 
been abnormal. 
Yet in another Lamellibranch, 
Angulus tener, much the same was 
seen: figure 1, drawn from camera 
sketches of the living egg with oe. 4, 
obj. 2 mm., indicates the ectosarcal 
waves and a polar body buried in 
the ectosare that surrounds it. In 
the two-cell stage 
marked ectosarcal 
waves rise up like 
frills on each side 
of the cleavage plane. When these cells 
divide to make four, the ectosare is seen to 
follow the groove as it sinks down, figure |p 
2, and not to leave the surface as Hammar sho n 
described in Echinus. When the actual cleavage plane cuts 
