24 GEOEGE JOHN EOMANES i875- 



species with a very large bell and a very small polypite. 

 Irritation of margin or radial tubes causes the animal to 

 go into a violent spasm, but irritation of the general 

 muscular layer only causes an ordinary locomotor 

 contraction. On cutting the whole animal into a spiral, 

 and irritating the extreme end of several marginal 

 strips, the entire muscular part of the spiral goes 

 into spasm. On interposing a great number of 

 interdigitating cuts in the course of the spiral, 

 there is no difierence in these results. Now the 

 question is. What is the nature of the tissue that 



conducts impressions 

 from the ganglionic 

 tissue to the muscular, 

 making the latter go 

 into a spasm? A spasm 

 is as different as pos- 

 sible from an ordinary 

 contraction, and will 

 continue to pass long 

 after the ordinary contractions have been blocked by 

 severity of section. It is scarcely possible to suppose 

 a nerve-plexus here — the tolerance towards section 

 being, so great, although it varies in different cases. 

 Besides, suppose this to be a segment of animal cut as 

 represented. On irritating margin at a all the bell 

 goes into a spasm, and it is evident that whatever the 

 nature of the conductile tissue, all the connections 

 must pass through the tract of tissue at b. Yet on 

 irritating that tract no spasm is given. I cannot 

 understand this on any view as to the nature of the 

 conductile tissue. 



