356 EDITH M. PRATY. 
3. Nervous Function.—As a stimulus affecting one 
polyp may be transmitted with gradually diminishing effect 
to its neighbours, it is probable that stimuli or impulses 
travel through this unspecialised amceboid protoplasmic 
plexus. As the speed of transmission might possibly be 
retarded by the presence of nutrient matter in the proto- 
plasm, the colonies would therefore become less sensitive to 
stimuli during the distribution of the digested food material. 
This may explain the fact that the colonies under experiment 
(p. 8332) withdrew their anthocodiz shortly after feeding, and 
remained in a contracted condition for several hours. 
In their amceboid character and multiple function these 
cells are homologous to the phagocytes occurring in other 
groups. 
The apparent lack of differentiation in their structure and 
function must be considered a secondary feature. Certain 
cells, at one time forming a constitutional part of the endo- 
derm, have reverted to a more primitive amoeboid condition, 
in which they are capable of fulfilling any function which the 
demands of the colony may require them to perform. 
The research in connection with this paper has been 
carried out in the Zoological Laboratories of the Victoria 
University of Manchester, in the Biological Laboratory of 
Port Erin, and in the Zoological Laboratory at Naples. 
I am greatly indebted to Professor Hickson for much 
valuable advice and kind supervision of my work. 
LITERATURE. 
1833. Quoy et Gaimarp.—‘ Voyage de |’Austrolabe,’ tome iv (Zoologie), 
Paris. 
1834. EurensBere, C. G.—‘ Die Corallthiere des Rothen Meeres.’ 
1848. Dana, J. D.—* Zoophytes,” ‘ United States Exp], Expedition.’ 
1877. Kuunzincer, C. B.—‘ Die Korallthiere des Rothen Meeres,’ erster 
Theil, “* Die Aleyonarien und Malacodermen,’ Berlin. 
1879. Hertwie, O. and R.—‘ Die Actinien,’ Jena, 1879. 
