As to my future intentions I can say very little about them.  With my present income, of course, marriage is rather a bad look out, but I do not think it would be at all fair towards Nettie herself to leave this country without giving her a wife’s claim upon me...It is very unlikely I shall ever remain in the colony.  Nothing but a very favourable chance could induce me to do so.

Much must depend upon how things go in England.  If my various papers meet with any success, I may perhaps be able to leave the service.  At present, however, I have not heard a word of anything I have sent.  Professor Forbes has, I believe, published some of Macgillivary’s letters to him, but he has apparently forgotten to write to Macgillivray himself, or to me.  So I shall certainly send him nothing more, especially as Mr. Macleay (of this place, and a great man in the naturalist world) has offered to get anything of mine sent to the Zoological Society.

[In the paper mentioned in the letter of March 21, above ("On the Anatomy and Affinities of the Family of the Medusae"), Huxley aimed at] “giving broad and general views of the whole class, considered as organised upon a given type, and inquiring into its relations with other families,” [unlike previous observers whose patience and ability had been devoted rather to] “stating matters of detail concerning particular genera and species.” [At the outset, section 8 ("Science Memoirs” 1 11), he states—­]

I would wish to lay particular stress upon the composition of this (the stomach) and other organs of the Medusae out of two distinct membranes, as I believe that it is one of the essential peculiarities of their structure, and that a knowledge of the fact is of great importance in investigating their homologies.  I will call these two membranes as such, and independently of any modifications into particular organs, “foundation membranes.”

[And in section 56 (page 23) one of the general conclusions which he deduces from his observations, is]

That a Medusa consists essentially of two membranes enclosing a variously-shaped cavity, inasmuch as its various organs are so composed,

[a peculiarity shared by certain other families of zoophytes.  This is a point which that eminent authority, Professor G.J.  Allman, had in his mind when he wrote to call my attention

“to a fact which has been overlooked in all the notices I have seen, and which I regard as one of the greatest claims of his splendid work on the recognition of zoologists.  I refer to his discovery that the body of the Medusae is essentially composed of two membranes, an outer and an inner, and his recognition of these as the homologues of the two primary germinal leaflets in the vertebrate embryo.  Now this discovery stands at the very basis of a philosophic zoology, and of a true conception of the affinities of animals.  It is the ground on which Haeckel has founded his famous Gastraea Theory, and without it Kowalesky could never have announced his great discovery of the affinity of the Ascidians and Vertebrates, by which zoologists had been startled.”]