96 PROCEEDINGS OF THE AMERICAN ACADEMY. 



lu this table the first columu names the subjects, of which there are as 

 many as there are numbers of glands, viz. to 10. In the succeeding 

 columns on a single line is exhibited the distribution of the number of 

 glands on the corresponding left legs. The column headed " Means of 

 Lefts " gives the average number of glands on the left legs of the indi- 

 viduals which make up the corresponding subject. The column headed 

 "Deviation of Rel. («f,. )" gives the deviations of the corresponding 

 " Means of Lefts " from the mean number of left male glands. The 

 column " Dev. of Subject (t^ ) " gives the deviation of the subjects from 

 their mean number. The last column is the quotient of d,. divided by c?,. 

 This gives r, r', r" , etc. The last number in the column is the mean of 



all these values of r. This number multiplied bv -^ will give R^ the 



1 1 T^ ^< ( 1.41083\ . , . , , T 1 



value sought. iJut —r- = -t———7^\ is nearly unity, so that the Index 

 * A, \ 1.4108'jy ^ •" 



of Correlation of the number of glands of the right and left legs is .772. 



Galton has shown that the same ratio holds true when relative and 



subject are interchanged. 



By a process similar to the preceding we have found that the ratio of 

 correlation of right and left legs in the female is .783. This ratio is so 

 similar to that obtained for males as to justify the conclusion that the 

 index of correlation in variahility of the leg glands is approximately equal 

 in the two sexes, and is about .111. 



The conclusions from this study may now be summed up. We have 

 in the leg glands of swine a serially arranged system of organs develop- 

 ing, for the most part, in one line, starting at one point, and extending 

 out a variable distance. On such a system of organs we investigate 

 quantitatively the question, How closely similar are the morphogenic 

 processes which determine the resemblance of these glands on the oppo- 

 site sides of the body and in the two sexes? First of ail, the average 

 number of glands is tolerably but not strikingly close on the two fore 

 legs and in the two sexes. The glands are nearly 1% more abundant in 

 the male than in the female. AVhen we come to study their variability 

 we find that the variants are distributed in accordance with the proba- 

 bility curve, very nearly. (See diagram.) A curious lack of symmetry 

 results from the fact that, since the mean lies at 3.5, variation is limited to 

 3.5 in one direction, but is unlimited (reaches as a matter of fact to 6.5) 

 in the other. The degree of variability in the right and left legs is, 

 especially in the case of the male, strikingly similar, being 1.41089 and 

 1.41083 in the two cases respectively, the difference being within the 



