Chap, v.] CORRELATED VARIATION. 179 



The nature of the bond is frequently quite obscure. 

 M. Is. Geoffroy St. Hilaire has forcibly remarked, that 

 certain malconformations frequently, and that others 

 rarely, co-exist, without our being able to assign any 

 reason. What can be more singular than the relation 

 in cats between complete whiteness and blue eyes with 

 deafness, or between the tortoise-shell colour and the 

 female sex; or in pigeons between their feathered feet 

 and skin betwixt the outer toes, or between the pres- 

 ence of more or less down on the young pigeon when 

 first hatched, with the future colour of its plumage; 

 or, again, the relation between the hair and teeth in 

 the naked Turkish dog, though here no doubt homol- 

 ogy comes into play? With respect to this latter case 

 of correlation, I think it can hardly be accidental, 

 that the two orders of mammals which are most 

 abnormal in their dermal covering, viz., Cetacea (whales) 

 and Edentata (armadilloes, scaly ant-eaters, &c.,) are 

 likewise on the whole the most abnormal in their teeth; 

 but there are so many exceptions to this rule, as Mr. 

 Mivart has remarked, that it has little value. 



I know of no case better adapted to show the impor- 

 tance of the laws of correlation and variation, inde- 

 pendently of utility and therefore of natural selection, 

 than that of the difEerence between the outer and inner 

 flowers in some Compositous and TJmbelliferous plants. 

 Every one is familiar with the difference between the 

 ray and central florets of, for instance, the daisy, and 

 this difference is often accompanied with the partial or 

 complete abortion of the reproductive organs. But in 

 some of these plants, the seeds also differ in shape and 

 structure. These differences have sometimes been at- 

 tributed to the pressure of the involucra on the florets. 



