60 ON CORRELATIONS OF GROWTH, WITH A SPECIAL EXAMPLE 



inter-maxillaries, or of the representatives of the Polian vesicles in 

 the Arenicola. 



But many of Mr. Paget's instances cannot be brought under this 

 head, and constituted as our minds are, we cannot but read them 

 as he has done. 



Mr. Darwin, on the other hand, himself admits 1 that there are 

 many instances of correlated growth of which our reason can give 

 no rationale, either as subserving ends, or as conforming to type, 

 or as speaking of parentage, or as working up into structure what 

 would else be waste and excretory ; for which in other words it can 

 assign neither final, nor formal, nor material cause. I would in- 

 stance, in addition to those he brings forward, the correlations of 

 growth witnessed in Morbus caeruleus betwixt a malformation of 

 the heart and a clubbed adunque state of the finger-nails, and in 

 Morbus Addisoni betwixt disorganised supra-renal capsules and pig- 

 mentary skin-discolouration. Unable to rationalise, we class such phe- 

 nomena as these under the wide head of ' Correlations of Growth. 5 

 The very vagueness of the phrase prevents us from even momentarily 

 deluding ourselves with the idea that it amounts to an explanation, 

 and to more therefore than an expression of facts. It cannot be 

 accused of striving to conceal the flimsiness of its thought by a 

 magnificent display of archaic words, as certain exchequers would 

 fain conceal their bankruptcy from the world by a copious issue of 

 paper-money. Herein lies its great merit. 



On a future occasion I shall consider the nature of the hyber- 

 nating glands, if so they may be called, of certain hybernating and 

 non-hybernating Insectivora and Chiroptera, and the possibility of 

 classing them as growths tautogeneous with the highly-developed 

 mesenteric and cervical lymphatic glands found in so many of those 

 creatures. 



And before concluding I would mention yet another class of 

 structures, the existence of which admits of being rationalised upon 

 yet another principle. These structures, fixed and settled in the 

 adult organism, speak of a time when the sex was as yet unfixed 

 and unsettled in the developing embryo, and accessory organs of 

 either kind were, if so we may say, prepared so as to be in readiness 

 to meet either event. The mammary glands, the Weberian organ, 

 and the cysts of Morgagni of the adult male, the round ligament 

 1 ' Origin of Species,' pp. 145, 197, 1st edit. ; pp. 162, 217, 3rd edit. 



