Raymond Roussel had decided to add illustrations to Nouvelles Impressions d'Afrique (1932) , and through the efforts of the GERON Detective Agency, contacted the artist and illustrator Henri Zo (1873 - 1933) best known for dramatic scenes of bullfighting in oils, and for illustrating Pierre Loti's Ramuntcho of 1923. The author briefed artist over the 'phone with generalised descriptions of scenes he wished visualised, and accepted without further intervention, the drawings he received.

The American novelist Gilbert Sorrentino (1929-2006) paid a tribute to the visual quality Zo infused into Roussel's book." Under the Shadow has a structure based upon the drawings done for Raymond Roussel's Nouvelles Impressions D'Afrique by H. A. Zo, drawings that, incidentally, have nothing to do with the text, but which, oddly enough, make a text of their own, a fragmented and discontinuous one, but a text nonetheless. Under the Shadow is Zo's "story" as it can be pulled out of his pedestrian but really haunting drawings." Interview with Alexander Laurence in 1994.

see Mark Ford, Raymond Roussel and the Republic of Dreams, Faber and Faber 2000

Francois Caradec, Raymond Roussel the Biography, Atlas Press London 2001