[The history of congenital malformations with special reference to conjoined twins. 2. The 18th to the 20th centuries].

Thoughts concerning teratology became increasingly scientific in the 18th century, and research into congenital malformations received a considerable impetus through discoveries concerning early embryonic development. The term "teratology" was coined in the 19th century and the introduction of photography enabled truly objective illustrations. Animal experiments were carried out to an increasing extent, the work of Roux and Speman being particularly notable. The great interest in teratological research in the 20th century was stimulated by observation of the effects of viral infection, radioactivity, thalidomide and diosin on embryonal development. This has led to the current major research capacity available to identify the causes of congenital malformation and to prevent them.