TRANSMISSION OF MODIFICATIONS 365 



proof of a causative relation, so quick are we to accept for fact 

 that which is not only plausible but startling. In this way a 

 mass of evidence (?) has accumulated on this subject second in 

 amount only to that bearing upon birthmarks and upon the 

 " control of sex." 



The law of chance. Before subjects of this character can 

 be properly studied, the operations of the mathematical law of 

 chance must be comprehended and their effects deducted. 



If we toss a coin the odds are even that " heads " will be up ; 

 they are also even for " tails up." There being but one alterna- 

 tive, either heads or tails is certain to appear. When the next 

 toss is made the odds are again even, but there is no causative 

 relation between the first and second events. They may agree 

 or they may differ; that is, both may be heads, both may be 

 tails, or one may be heads and the other tails. 



Successive tosses will give rise to an extremely irregular 

 series, as may be shown by trial. However, if the series be 

 continued indefinitely and tally be kept, it will be found that in 

 the long run the heads and the tails will be equal. When the 

 equality will first occur is entirely uncertain. It may be at the 

 second throw or it may be at the hundredth, or even later, but 

 it is certain to come. 



The roulette wheel, as commonly used, is made up of thirty- 

 seven color spaces, eighteen red and nineteen black, or the 

 reverse. The wager is laid upon the number or the color on 

 which the wheel will rest after a supposedly impartial spin. It is 

 evident that the probability of its resting upon a particular num- 

 ber is but one in thirty-seven if the wheel is mechanically per- 

 fect, and that the chances of its resting upon a particular color^ 

 are not quite even. This difference of nineteen to eighteen 

 constitutes the ''advantage" of the owner over the player, and 

 shows the hopelessness of attempting to " break the bank." 

 This margin of one out of every thirty-seven bets is over 2.5 

 per cent of the business and constitutes the assured profit in a 

 game of chance conducted honestly on this plan, which is 

 the one in use at Monte Carlo, the greatest gambling house in 

 the world. 1 



1 See Pearson, Chances of Death, pp. 42-62. 



