An Introduction to a Biology 

 II 



Weldon's experiment may be varied in the following 

 way. Instead of staining 6 dice red and leaving the six red 

 dice of the first throw on the table to form half of the second 

 throw, we may stain some other number, say 9, and allow 

 9 dice to pass over from the first to the second throw. In 

 fact, we may stain and leave over from the first to the second 

 throw any number of dice from to 12 inclusive. Table 

 shows the result of 500 pairs of throws, in which, to make 

 the second throw in each pair, all the dice were gathered up 

 from the table and thrown again. In this case there is no 

 correlation between the two throws. Table I. shows the 

 result of 500 pairs of throws, in which to make the second 

 throw, all the dice except one were gathered up from the 

 table and thrown again. In this case there is very slight 

 correlation between the two throws. To make Table II., 

 2 dice were left down. To make Table III., 3 were left down. 

 And so on. 1 To make Table XII., it did not matter whether 

 the dice were stained red or not, for the second throw was 

 merely the first throw counted over again. And the Table 

 consequently shows any given number in the first throw 

 always followed by the same number in the second. 



Each of the thirteen Tables which are seen on the Plate 

 was made by substituting for the Arabic numerals in each 

 square of Tables, to XII., a corresponding number of dots, 

 and then in erasing all the lines inside the four boundary 

 lines of the Table. 



The attempt to make the phenomenon of correlation 

 clear to an audience, previously unfamiliar with it, is in 

 my belief less likely to be successful if it is only possible to 

 show one Table such as VI., instead of a series of Tables 

 exhibiting at a glance the gradual increase in correlation 

 as shown by the transition from a circular blur to a diagonal 

 line, as seen in the Plate. The reason for this is the same 



1 I am indebted to Mr. Charles Biddolph for making all the throws, 

 except those which compose Tables 0, VI., and XII. 



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