448 G. H. PARKER AND E. G. TITUS 



they reach the band of longitudinal muscle, they often extend 

 up and down this band in intimate relations with its fibers 

 (fig. 7). Many of the fibrils that enter the muscle terminate 

 there in small knobs (compare fig. 7), which may be a simple 

 form of motor ending comparable to that which Wolff ('04, 

 p. 249) has described in Heliactis and Groselj ('09, p. 287) in 

 Bunodes; or these endings may be only apparent and mark the 

 point at which the impregnation ceased, not the real end of 

 the fibril. 



We regard these fibrils as neurofibrils and as the principal 

 part of the transmission system between the ectoderm of the 

 column wall and the longitudinal muscles of the mesenteries. 

 None of our preparations show these fibrils connected with 

 cells. It would seem that the method we have used stains 

 only the neurofibrillar substance and not the rest of the generat- 

 ing cell. Whether the cells that produce these neuro-fibrils 

 are those long since known to be in the supporting lamella 

 (fig. 4) and easily demonstrated by ordinary stains, or whether 

 they are cells in the ectoderm, we are unable to say. It seems 

 to us not improbable that some of the cell bodies identified by 

 Havet ('01, p. 395) in the mesogloeal regions of the body wall 

 in Golgi preparations may be those from which the neuro- 

 fibrils have come, but we agree with Kassianow ('08 b, p. 672) 

 in the belief that at least some of the bodies figured by Havet 

 as ganglion cells are artifacts, though we do not go so far as 

 to raise the question whether he saw any ganglion cells at all. 

 But however this may be, we are confident that the fibrils that 

 we have seen are an important part of the nervous connections 

 between the ectoderm of the column on the one hand and the 

 longitudinal muscles of the mesenteries on the other, and that 

 these connections are in the main through the supporting lamella. 

 Our results are thus opposed to the conclusion drawn by the 

 Hertwigs ('79-80, p. 50) namely, that the ectodermic nervous 

 system of actinians is in connection with the entodermic only 

 through the oesophagus, and confirm the observations of Havet 

 to the effect that there are mesogloeal connections between 

 these two systems, as was long ago maintained by von Heider 



