CORRELATION OF GROWTH. 55 



which we now only know as occurring in association, may 

 ultimately be found dissociated, and conjoined with other 

 structures of a different character. 



The term "correlation of growth" may also be applied 

 to those obscure relations which are found to subsist be- 

 tween certain organs, which have no perceptible connection 

 with one another, but which are nevertheless bound together 

 by some very intimate " sympathy." Thus, the full develop- 

 ment of the organs of reproduction is often accompanied by 

 more or less conspicuous changes in structures which would 

 appear to be very remotely connected with the generative 

 functions. In man, for example, the period of puberty is 

 marked, as a rule, by the growth of hair, and by alterations 

 in the form of the organs of voice. Still more striking ex- 

 amples of this obscure phenomenon might be adduced as 

 regards the " sympathies " shown between certain organs 

 when diseased. In some of these cases, as in the case of 

 the "sympathy" between the mammary glands and the 

 uterus, it might be said that the two organs are members of 

 one system; but there are instances (as, for example, in 

 " mumps ") in which the sympathising organs appear in a 

 state of health to be absolutely unconnected, and to exercise 

 no influence upon each other. 



