1876 MEDUSA 31 



substance before spoken of is the seat of this physio- 

 logical continuity is here immaterial.) Dr. Foster 

 fully agrees with me in this deduction from my ex- 

 periments, and is very pleased about the latter, thus 

 afiording additional support to his views. But what 

 I want to ask you is, supposing the interfascicular 

 substance to have no share in conducting stimulus 

 (and I have no evidence of its presence in Sarsia), 

 and hence that the properties of nerve and muscle 

 are united in the contractile fibres of ]\Iedusae — sup- 

 posing this, do you think that the peculiarity you 

 observed in the molecular conformation of this tissue, 

 considered as muscular, is likely to have anything to 

 do with this peculiarity in its fimction ? 



I know you do not like theory, so I shall return 

 to fact. There can be no doubt whatever that the 

 seat of spontaneity is as much locaHsed in the 

 margin as the sensibihty to stimulus is diffused 

 throughout the bell. There must, therefore, be some 

 structural difference in the tissue here to correspond 

 to this great functional difference. Agassiz is very 

 positive in describing a chain of cells running round 

 the inner part of the marginal canal. Now, although 

 I sometimes see a thin cord-like appearance here, I 

 should not dare to say it was nervous. Gold cer- 

 tainly stains it, but it also stains many other parts 

 of the tissue, and until I can see cells here I cannot 

 be sure about a visible nervous cord. The cord I do 

 see may be the wall of the marginal canal. I intend 

 to persevere, however, trying your suggestions, also 

 osmic acid. 



I can get no indications of electrical disturbance 



