To summarize from Francis Dov Por's "The Road to the International Society of Zoological Sciences" "Zoology ... was among the very first disciplines to build an international organization. Congresses of Zoology started in 1889 on the initiative of the Société zoologique de France on the occasion of the International Exposition in Paris. Congresses were then held at regular intervals and attendance increased from congress to congress, from a few tens in Paris and in Moscow to 700 in Budapest in 1927. The London Congress set a target of 1000 and in Washington the number reached 2500.