CHAPTER Y. 
EXPERIMENTS IN SECTION OF NAKED-EYED MEDUS&. 
Distribution of Nerves in Sarsia. 
My experiments have shown that the nervous 
system in the naked-eyed Medusz is more highly 
organized, or integrated, than it is in the covered- 
eyed Medusze; for whereas in the latter I obtained 
no evidence of the gathering together of nerve- 
fibres into definite bundles or trunks (the plexus 
being evenly distributed over the entire surface of 
the neuro-muscular sheet lining the umbrella), in 
the former I found abundant evidence of this 
advance in organization. And as the experiments 
in this connection serve to substantiate the histo- 
logical researches of Professors Haeckel, Schultz, 
Eimer, and Hertwig, in as far as the distribution of 
the main nerve-trunks is concerned, I shall here 
detail at some length the character and results of 
these experiments in the case of Sarsia. 
The occurrence of reflex action in Sarsia is of 
a very marked and unmistakable character. I may 
begin by stating that when any part of the internal 
surface of the bell is irritated, the manubrium 
responds; but as there is no evidence of ganglia 
