into Flemish art. Many of his works are small historical, allegorical and biblical cabinet paintings with the focus on figures. He also invented or popularized several new themes that became popular in Flemish painting, such as genre scenes populated by monkeys (also referred to as singeries) and Kunstkammer or gallery paintings displaying a wealth of natural and artistic treasures against a neutral wall. Frans Francken the Younger introduced many other unusual themes that later became popular, such as the 'Triumphal Procession of Amphitrite' and 'Croesus and Solon'. Francken also made a series of paintings depicting witches and witchcraft, including portrayals of witches' sabbats. Frans Francken the Younger signed his works with 'de jonge Frans Francken' ('the young Frans Francken') before the death of his father in 1616. From the late 1620s he used the signature 'de oude Fr. Francken' ('the old Fr. Francken'), to distinguish himself from his son Frans III. His father had also started signing his paintings with 'den oude Frans Francken' ('the old Frans Francken') after Frans Francken the Younger had become active as an artist. His paintings are held by most major museums in Europe. Collaborations Francken was particularly skilled in painting the human figure, a fact which is confirmed on some of the portraits of the artist that were etched by Anthony van Dyck and carry the Latin inscription: 'ANTVERIÆ PICTOR HVMANARVM FIGVRARVM' (Figure painter of Antwerp). He was frequently invited to contribute figures in compositions by other artists, such as the landscape artists Tobias Verhaecht, Abraham Govaerts and Joos de Momper, the architectural painters Pieter Neeffs the Elder, Pieter Neeffs the Younger, Hendrik van Steenwijk I, Paul Vredeman de Vries and Bartholomeus van Bassen and flower painters such as Jan Brueghel the Elder and Andries Daniels. Allegorical paintings A large portion of the output of Frans Francken the Younger consisted of allegorical paintings. An example is the Allegory on the Abdication of Emperor Charles V in Brussels (Rijksmuseum). The composition is an allegorical representation of the abdication of Emperor Charles V in Brussels. Charles V who is dividing his empire after a life of continuous warfare and ill health is seated on his throne flanked by his successors Ferdinand I and Philip II. In front of Philip the personifications of the territories of the Empire with their banners are kneeling down. In the foreground the personifications of the continents America, Africa, Europe and Asia