80 COERELATED VARIATIONS. 



CARAPACE LENGTH CARAPACE LENGTH TELSON AND 



AND TERGUM VI. AND TELSON. TERGUM VI. 



Plymouth, .09 .18 -.11 



Southport, .06 .14 -.09 



Professor Weldon points out that the above results 

 lead us to hope that it may be possible to determine con- 

 stants for any species of animal which would " give an 

 altogether new kind of knowledge of the physiological 

 connection between the various organs of animals, while 

 a study of those relations which remain constant 

 through large groups of species would give an idea, at- 

 tainable at present in no other way, of the functional 

 correlations between various organs which have led to 

 the establishment of the great sub-divisions of the ani- 

 mal kingdom." 



In a subsequent paper,* Professor Weldon deter- 

 mined no less than 23 different correlation constants, 

 between various pairs of organs in 1000 adult female 

 crabs (Carcinus mcenas), collected in Plymouth Sound, 

 and in another 1000 collected in the Bay of Naples. 

 He found that there was as a rule a remarkable degree 

 of correspondence between the values of r derived from 

 an investigation of the same pair of organs in the two 

 races examined. There were in some cases consider- 

 able differences between the values, it is true, but Wel- 

 don considers that these were in no case sufficient to 

 justify the assertion that the degree of correlation is 

 really different in the two cases. It should be men- 

 tioned, however, that Professor Pearson f does not 



*Proc. Roy. Soc., liv. p. 318. 

 f Phil. Trans. 1896, A. p. 267. 



