Berger, an experienced specialist in nervous diseases, concluded, in his Vorlesungen, that 99 per cent. of young men and women masturbate occasionally, while the hundredth conceals the truth;[290] and Hermann Cohn appears to accept this statement as generally true in Germany.  So high an estimate has, of course, been called in question, and, since it appears to rest on no basis of careful investigation, we need not seriously consider it.  It is useless to argue on suppositions; we must cling to our definite evidence, even though it yields figures which are probably below the mark.  Rohleder considers that during adolescence at least 95 per cent. of both sexes masturbate, but his figures are not founded on precise investigation.[291] Julian Marcuse, on the basis of his own statistics, concludes that 92 per cent. male individuals have to some extent masturbated in youth.  Perhaps, also, weight attaches to the opinion of Dukes, physician to Rugby School, who states that from 90 to 95 per cent. of all boys at boarding school masturbate.[292] Seerley, of Springfield, Mass., found that of 125 academic students only 8 assured him they had never masturbated; while of 347, who answered his questions, 71 denied that they practiced masturbation, which seems to imply that 79 per cent. admitted that they practiced it.[293] Brockman, also in America, among 232 theological students, of the average age of 231/2 years and coming from various parts of the United States, found that 132 spontaneously admitted that masturbation was their most serious temptation and all but one of these admitted that he yielded, 69 of them to a considerable extent.  This is a proportion of at least 56 per cent., the real proportion being doubtless larger, since no question had been asked as to sexual offenses; 75 practiced masturbation after conversion, and 24 after they had decided to become ministers; only 66 mentioned sexual intercourse as their chief temptation; but altogether sexual temptations outnumbered all others together.[294] Moraglia, who made inquiry of 200 women of the lower class in Italy, found that 120 acknowledged either that they still masturbate or that they had done so during a long period.[295] Gualino found that 23 per cent. men of the professional classes in North Italy masturbate about puberty; no account was taken of those who began later.  “Here in Switzerland,” a correspondent writes, “I have had occasion to learn from adult men, whom I can trust, that they have reached the age of twenty-five, or over, without sexual congress. ’Wir haben nicht dieses Beduerfniss,’ is what they say.  But I believe that, in the case of the Swiss mountaineers, moderate onanism is practiced, as a rule.”  In hot countries the same habits are found at a more precocious age.  In Venezuela, for instance, among the Spanish creoles, Ernst found that in all classes boys and girls are infested with the vice of onanism.  They learn it early, in the very beginning of life,