340 
ZOOLOGY: PARKER AND TITUS 
gles to the longitudinals and extend from the outer wall of the sea- 
anemone to the inner free edge of the mesentery or to the oseophagus 
when the mesentery unites with that organ. The parietal muscles of 
the mesenteries are longitudinal strands in the mesenteries at the re- 
gion of attachment of these organs to the column wall. The circular 
muscle of the column covers the entodermic face of the column wall. 
The sphincter is a specialized band in the circular muscle of the column 
wJiich it surrounds at a level close to the oral disc. The longitudinal 
muscles of the acontia are extremely tenuous muscles in these filamen- 
tous organs. 
The nervous system of sea-anemones consists of sense cells said to 
be in the entoderm as well as in the ectoderm whose deep ends form a 
nervous network in close proximity to the muscles. This network in- 
cludes in its meshes ganglion cells. In 1879 the Hertwigs described a 
concentration of nervous material in the oral disc of sea-anemones and 
believed this to be the beginnings of a central nervous organ. Grosely 
claimed that the nervous centralization is in the oesophagus. Many 
recent workers, however, have declared the nervous system to be dif- 
fuse and not centralized at all. 
According to most investigators the ectodermic nervous network con- 
nects with the entodermic one only in the region of the mouth where 
these two layers are confluent being separated in other places by the 
supporting lamella. Havet, however, in 1901 claimed that nervous 
tissue could be traced through the supporting lamella thus connecting 
ectoderm and entoderm directly. We have found evidence of this both 
histological and physiological. By special staining methods we have 
confirmed Havet's statement that the supporting lamella contains 
nervous elements and by experiment we have shown that these elements 
connect the ectoderm directly with the longitudinal muscles of the mes- 
enteries (entoderm), that is, without passing through the mouth region. 
If a small area on the ectoderm of the column wall is stimulated mechan- 
ically or chemically, the sea-amenone will retract the oral disc through 
the action of the longitudinal muscles of the mesenteries. If this area 
is partially isolated by making a circular incision around it and complete- 
ly through the column wall so that it is attached to the animal only 
by the deep-lying mesenteries, the longitudinal muscles in these organs 
will regularly contract on stimulating its ectodermic face. Thus there 
must be direct nervous connections between the ectoderm of the column 
wall and the longitudinal muscles of the mesenteries, and this connec- 
tion appears to consist of a relatively complex but diffuse nervous met- 
v/ork. 
A second type of neuromuscular structure is seen in the outer layer of 
