The chromosome complement ofB. purpurocaeruleashows a pattern of Quinacrine bands of the reduced type, that coincides both with the pattern of Giemsa C-bands and with the Feulgen band pattern shown by GRAU (1966). Quinacrine staining provides the best definition of karyotype details. The correspondence of Q-bands of the reduced type to positively heteropycnotic Feulgen bands is also briefly discussed.