Animalculum _c_, fig. 8. mirabilissimæ erant structuræ, et plurima habebat membra. XXXIII. _Remarks on Dr._ Job Baster’s Observationes de Corallinis, &c. _printed above, p. 258. In a Letter to the Right Honourable_ George _Earl of_ Macclesfield, _President of the R. S. from Mr._ John Ellis, _F.R.S._ [Read June 9, 1757.] My Lord, I HAVE read Dr. Job Baster’s letter to the Royal Society; wherein he endeavours to prove, that corallines are not of an animal, but a vegetable nature; and has brought many arguments to support his system; which, to gentlemen not well acquainted with the subject, may appear plausible. I could have wished the Doctor had read and examined thoroughly what has been lately written on the subject: I then should not have had occasion to trouble your Lordship with the following remarks, which I find necessary to support what I have already advanced on that head. His first argument is, That because he does not find as many polypes in the corallines adhering to ships, flood-gates, and buoys, as in deep water on oysters, muscles, and rocks, therefore he concludes, that corallines are not formed by polypes. In answer to this, let us examine the pliable structure of these bodies, and how wisely nature has defended such tender substances with a tough thin membranaceous covering, and we shall find, that the sea is calm enough often near the surface to give them time to grow, even in the strongest currents: but, without doubt, they are more liable to be destroyed in such agitated situations, than in the calm depths of the sea. His second argument is, That finding polypes are not equally dispersed over the whole plant, how can they form it? and gives us an example, _Tab._ VIII. _fig._ 5. of a coralline, that is incrusted with many other corallines or polypes on the stem, but has none on the branches. Here we plainly see the mistake: the Doctor looks for the tender part of the polype on the surface of the coralline, considering it as a plant; and indeed, if this was the case, he ought so to do; but he never once takes notice of the internal hollow structure of the stem, branches, and denticles of those bodies, to inform us whether he found an animal in those parts or no. This material point he seems not to have thought on; which is really the true point in controversy at present among gentlemen, who have not examined these bodies recent in sea-water. His third argument is, That almost always one and the same coralline plant cherishes polypes of different kinds; and refers us to Tab. VIII. fig. 2. and 4.