I wish you would say what you think about this peculiarity in relation to a subject that I have been working up. You no doubt remember that in ----'s paper that we heard read, he said that the snail's heart had no nerves or ganglia, but nevertheless behaved like nervous tissue in responding to electrical stimulation. He hence concluded that in undifferentiated tissue of this kind, nerve and muscle were, so to speak, amalgamated. Now it was principally with the view of testing this idea about 'physiological continuity' that I tried the mode of spiral and other sections mentioned in my last letter. The result of these sections, it seems to me, is to preclude, on the one hand, the supposition that the muscular tissue of Medusæ is merely muscular (for no muscle would respond to local stimulus throughout its substance when so severely cut), and, on the other hand, the supposition of a nervous plexus (for this would require to be so very intricate, and the hypothesis of scattered cells is without microscopical evidence here or elsewhere). I think, therefore, that we are driven to conclude that the muscular tissue of Medusæ, though more differentiated into _fibres_ than is the contractile tissue of the snail's heart, is, as much as the latter, an instance of 'physiological continuity.' (Whether or not the interfascicular protoplasmic substance before spoken of is the seat of this physiological continuity is here immaterial.) Dr. Foster fully agrees with me in this deduction from my experiments, and is very pleased about the latter, thus affording 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 Medusæ--supposing 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 function?