The effect of neurohypophysial hormones has been tested in vitro on oviducts of four species of urodele and three species of anuran Amphibia. Contractile responses were obtained with all the hormones used but 8-arginine oxytocin (vasotocin) was usually most potent. The sensitivity of the oviducts varied widely from species to species; there were also pronounced seasonal differences within a species. Histological investigations yielded some information on the abundance and arrangement of muscle fibres in amphibian oviducts. A simple and sensitive (magnification up to \ m=x\ 1000) recording system for isotonic contractions is described.

It has been shown by now that the oviduct of birds, reptiles and amphibians in vitro gives a contractile reponse to low concentrations of neurohypophysial hormones (for references see Heller, Ferreri & Leathers, 1970). Fishes have been little investigated but it could be shown that the oviduct of some oviparous teleosts and the ovaries of certain ovoviviparous bony fishes are stimulated by vasotocin, ichthyotocin and oxytocin (Heller & Leathers, 1969). Attempts (Dreyer, 1946;Perks, 1959;Dodd, Perks & Dodd, 1966) to demonstrate effects of elasmobranch pituitary extracts or oxytocin on elasmobranch oviducts in vitro were unsuccessful because of persistent, strong, spontaneous contractions. Further experiments on elasmobranch oviducts seemed indicated because of (1) the positive results obtained in the other classes of cold-blooded vertebrates, (2) the possibility of finding a more suitable suspension fluid, (3) the availablity of purified elasmobranch neurohypophysial principles, and (4) a more sensitive method of recording (see Heller et al. 1970) than that used by previous authors.Strips of the distal (uterine) portion of the oviduct of both pregnant and nonpregnant Scyliorhinus caniculus were used immersed in the elasmobranch Ringer solution described by Prosser & Brown (1961) at 19-20°C. The strips responded to high concentrations of acetylcholine (10-40 ng/ml) and confirming Dreyer (1946) and Dodd et al. (1966) to nanogramme concentrations of adrenaline. Marked and longer-lasting contractions were also obtained in all of four experiments with simple acetic acid extracts (neutralized with NaOH) of the fish's own neurointermediate lobe (NIL), prepared immediately after killing at concentrations equivalent to 1/50-1/100 of the lobe per ml. However, since control extracts of cerebellar but not of olfactory lobe tissue produced a weak contractile response, the activity of the NIL extracts cannot or cannot completely be ascribed to neurohypophysial principles without further study. Synthetic arginine vasotocin at concentrations up to 40 ng/ml was ineffective even in dogfish which bad carried egg-cases in the distal portion of the oviduct. Synthetic oxytocin was tested on six uterine strips at concentrations of 6-40 ng/ml ; a clear contractile response was obtained in two oviducts, no effect in three, and a marked response in one, which, however, became very much weaker when the dose was repeated. It is perhaps not altogether surprising that the organ did not respond to arginine vasotocin since the NIL of Scyliorhinus (Heller & Roy,