In the Dr. Jacobus survey definite penis size differences on a basis of race were detected. The largest Arab penises were found to be between eight and ten inches; but it was among the Muslim Sudanese that Jacobus found "the most developed phallus" - notably "one of the maximum dimensions, being nearly 12 in. in length, by a diameter of 2- in."

The hardy researcher remarked that this was "a terrific machine" - "more likely the penis of a donkey than of a man." He concluded that the "Sudanese Negro possesses the largest genital organ of all the races of mankind". In a less extensive survey, but equally interesting, Dr. Robert Chartham measured erect penises for groups of men of various nationalities. The largest organs for each nationality were as follows:

• English - 10½ in.;
• West German - 8½ in.;
• Negro - 7½ in.;
• French - 7¾ in.;
• Danish 8 in.;
• American - 7¾ in.; and
• Swedish 7¾ in.

The groups were small, ranging from only 9 to 121 individuals; nevertheless the data acquired are not without significance.