From T. H. Huxley 17 December 1858
Der. 17th. 1858
My dear Darwin
Von Bärs work is called “Untersuchungen über die Entwickelungsgeschichte der Fische” & was published as a separate brochure in 1835— Appended to it is a special “Anhang” “Ueber die Schwimmblase der Fische” in which Von Bar particularly considers the homologies of the air bladder—1 He considers that the air bladder is developed as a diverticulum of the wall of the anterior part of the alimentary canal— The connecting duct remains open in some Fishes but is obliterated in others— He thinks however that the anterior division of the air bladder, in such Fishes as the Carp, arises independently of the posterior division (or true air bladder) in connexion with the auditory organs, and only opens afterwards into the posterior air bladder
Vogt (“Embryologie des Saumones” in Agassiz. Poissons d’Eau douce)2 gives an account of the development of the air bladder which agrees in essentials with that of Von Baer. Both agree in stating that the young fish fills its air bladder by swallowing air—at the surface of the water and Von Bar even thinks that for a time the young fish respires in this way—
Von Bär winds up thus
“The air bladders of Fishes which form parts of a pneumatic apparatus are of at least two kinds; the one is analogous to the Tympanum & Eustachian tube of the higher animals; the other is indeed an outgrowth of the alimentary canal but has only a general analogy with the lungs of the higher animals; it is rather a body sinus (Rumpf-sinus) whose principal function must be to render the body of the fish specifically lighter—though some influence upon the composition of the blood may be exerted at the same time”3
Structurally the air bladder of Polypterus is altogether a batrachian lung—but it differs from a true lung in its blood not being returned to the heart
Ever yours truly | T H Huxley
CD annotations
Footnotes
Bibliography
Baer, Karl Ernst von. 1835. Untersuchungen über die Entwickelungsgeschichte der Fische; nebst einem Anhange über die Schwimmblase. Leipzig.
Natural selection: Charles Darwin’s Natural selection: being the second part of his big species book written from 1856 to 1858. Edited by R. C. Stauffer. Cambridge: Cambridge University Press. 1975.
Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.
Summary
K. E. von Baer’s view of the air bladder of fishes.
Letter details
- Letter no.
- DCP-LETT-2381
- From
- Thomas Henry Huxley
- To
- Charles Robert Darwin
- Sent from
- unstated
- Source of text
- DAR 166: 289
- Physical description
- ALS 4pp †
Please cite as
Darwin Correspondence Project, “Letter no. 2381,” accessed on 23 April 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-2381.xml
Also published in The Correspondence of Charles Darwin, vol. 7