The Brazilian writer Marques Rebelo (1907-1973) once wrote in one of your
fictional books (The Trapicheiro River) about the Toscanini's debut as a
conductor here in Brazil.  Here is an extract of his book (I'm giving you
a free translation from the original Portuguese version):

   "It was in Rio de Janeiro that Tita Ruffo revealed his art to the
   audience.  Also Toscanini.  Great times!  Great times when there were
   real lyric companies and the audience was competent and demanding
   (...) Toscanini came [to Brazil] as a violoncelist of the orchestra,
   because at that time the companies used to bring their orchestras.
   By the way, a fine violoncelist!  The maestro felt ill suddenly -
   the yelow fever, my children, the terrible yellow fever!  And the
   theatre was already packed, impatient, waiting.  Aida was on the
   programme.  The manager was desperate, without knowing what to do,
   when Toscanini - he was only 19 years old - offered to replace the
   maestro, pushed by his colleagues that knew that he was able to
   conduct.  He took the baton and conducted the score by heart.  It
   was a triumph!  The audience got crazy!  He left the instrument and
   nowadays he is the best conductor of the world!"

Do any listers know about this episode in Toscanini's life? Who was in the
cast (certainly Tita Ruffo was)??

Wilson Pereira.