Highland Amphibians and extremly diluted thyroxine

Aim: To document an international multicentre research project (1990-2012, pdf) including inter-laboratory and independent repetition of experiments on the effect of highly diluted thyroxine on the metamorphosis of highland amphibian larvae. Research papers (see links) were published in peer reviewed, mostly PUBMED / MEDLINE listed journals.

Methods: Thyroxine was used because this hormone plays a key role in amphibian metamorphosis. Starting from a dilution of 10-4 parts by weight of tetra-iodo-thyronine sodium pentahydrate, the substance T30x was obtained by 26 successive steps of tenfold dilution in pure water, followed by vigorous agitation and was tested versus analogously prepared water (W30x). Grass frog rana temporaria were taken from alpine biotopes and were treated with T30x or W30x from the 2-legged stage on by adding 3microL of probes per animal to the basin water at intervals of 48h. Two end-points were considered: first, entry into the 4-legged stage, and second, tail reduction. All experiments were performed blind.

Experiments were performed since the early 1990s by the initial team (P. C. Endler, based at that time at Graz University (pdf) and W. Scherer-Pongratz at the Graz Boltzmann Institute (pdf)) and by independent researchers (R. van Wijk from Utrecht University (pdf), H. Lassnig from the Federal Institute of Veterinary Medical Investigation Graz (pdf), C. Zausner-Lukitsch from Vienna University (pdf), a researcher suggested by KIKOM, Bern University (pdf) and B. Harrer from Patienteninformation fuer Naturheilkunde Berlin (pdf)). A total of 22 sub-experiments were performed, each involving 60–100 animals per group, 15 by the initial team and 7 by the 5 independent researchers.

Results: Independent Metaanalysis (pdf) shows that in most sub-experiments – the sole exception being two performed and reported by the initial team themselves – a trend was found of T30x-animals being slower (up to 6 h within 3 days) than W30x-animals. Pooled T30x values obtained by the initial team were 10.4% smaller than W30x values (100%) (p < 0.01 and d > 0.8), and pooled T30x values from the 5 independent researchers were 12.4% smaller (p < 0.01 and d > 0.8), i.e. differences between groups were statistically highly significant and the effect size was large in either case. Analogously, the number of animals entering the juvenile stage with reduced tail was smaller for T30x than for W30x. For details, see Experiments 1990 (pdf), Repetition 2002 (pdf), Repetition 2010 (pdf), Repetition 2012 (pdf).

Conclusion: A metamorphosis hormone diluted beyond Avogadro’s limit using a process of stepwise dilution and agitation according to instructions of homeopathy produced a clear trend of metamorphosis inhibition. This was observed by and raw data (zipped pdf and xls) were made accessible by 7 researchers from Austria, Germany, Switzerland and the Netherlands.

Annotation: Similarly, experiments on climbing activity (pdf) of highland frogs were repeated within the team (pdf). A detailed account of the difficulties when using lowland animals (pdf), a bibliometric survey on the international state of repetition of fundamental research experiments (pdf), backstage report (pdf) and an anthology “Ultra High Dilution” (pdf) have been published previously. Experiments on metamorphosis of highland frogs are ongoing. The authors are interested in an open-minded interdisciplinary discussion of results and research strategies.


Endler P.C., Pongratz W., van Wijk R., Kastberger G., Haidvogl M. Effects of highly diluted succussed thyroxin on metamorphosis of highland frogs. Berlin J Res Hom 1991; 1: 151-160.

Zausner C., Lassnig H., Endler P.C., Scherer W., Haidvogl M., Frass M., Kastberger G., Lüdtke R. Die Wirkung von "homöopathisch" zubereitetem Thyroxin auf die Metamorphose von Hochlandamphibien. Ergebnisse einer multizentrischen Kontrollstudie. Perfusion 2002; 17: 268-276.

Interuniversitäres Kolleg. Pilotversuch zur unabhängigen Wiederholung einer Studie zur Metamorphose von Amphibienlarven und homöopathisch verdünntes Thyroxin (10e-30) durch eine von der Kollegialen Instanz für Komplementärmedizin der Universität Bern vorgeschlagene Forscherin. Bericht an das Amt der Steiermärkischen Landesregierung, Fachabteilung 10 A. Graz, 2010.

Harrer H. Replication of an experiment on extremely diluted thyroxine and highland amphibians. Homeopathy 2013; 102: 25-30.