388 WILLIAM A. HILTON 
Torrey (01) gives a description of the nervous system of this 
form from sections, but his material must have been poorly fixed, 
for in well-preserved specimens the central nervous system is 
continuous laterally with the lophophore organs as well as with 
the lateral longitudinal cord. 
The best results from the study of serial sections were obtained 
after Flemming or mercuric chloride fixation followed by one of 
the haematoxylin methods. In well-preserved specimens the 
general structure of the neuro-epithelium was well shown. 
Besides the usual epithelial cell, there were three other types 
recognized: the bipolar sense cells, especially shown in methylene 
blue in various parts of the body; the supportive cells with the 
slender fibers running through the thickness of the epithelium 
and nerve fibers layer, and the nerve cells partly in the epithelium, 
partly in the fibrous portion. The fibers run laterally at various 
levels. 
CONCLUSIONS 
1. The nervous system of Phoronis is only partly separated 
from the epithelium. 
2. There is a distinct center or a central nervous system where 
fibers and cells are more abundant. 
3. The lophophoral organs are well developed and may be sense 
organs. 
4. The left longitudinal cord, which may not be nervous tissue, 
is distinctly connected with the central nervous system. If not 
a nerve structure, it must be some sort of sense organ. 
5. Tentacles and body have bipolar sense cells in little groups. 
6. The nervous system controls the muscular system as 
shown by the use of anesthetics. The tentacles recover last and 
are affected first by chloretone. 
7. The movements are: a) Ciliary currents on the tentacles 
probably not under nerve control. 6) Contractions of the 
tentacles at least partly under nerve control. c) Contractions of 
the body stimulated through the surface of the body at almost 
any point, especially by tactile stimuli Just below the tentacles. 
