ON CORRELATIONS OF GROWTH. 57 



morphological considerations, seemed firmly established in a country 

 delighting in compromises ; the legitimacy of the one, and the 

 prescriptive right of the other, placed them, when united, in an 

 apparently unassailable position. The appearance of the theory of 

 complemental nutrition in a deservedly well-known work 1 caused 

 men to accept of a triumvirate of ruling causes. Material causes 

 counted for something as well as final and formal ; Wolff's theory 

 could suffice not only for the rationalisation of many phenomena 

 which Paley and Oken did explain, but also for the elucidation of 

 some with which their philosophies were incompetent to deal. 

 Mr. Paget's exemplifications of the law of complemental nutrition 

 seem drawn exclusively from a class of cases of what I would call 

 ' heterogeneous growth.' The evolution of the one structure has 

 rendered possible the evolution of the other, by setting free some 

 residual product which Nature in her economy has worked up into 

 such secondary structure. The perfecting of the plumage con- 

 temporaneously with the perfecting of the sexual functions in the 

 pairing bird is- one, and may serve as a type of all, of the instances 

 given by Mr. Paget. There is no equality in rank between the 

 two structures, which stand to each other in this relation of com- 

 plemental nutrition ; the one is supported by what the other finds 

 useless, superfluous, or even hurtful ; after the production of the 

 one the organism aims and labours, the other is but a ' neben- 

 produkt ; ' they are heterogeneous in the same sense as the food of 

 the hound and the food of his master, and often in a yet truer 

 sense still. 



The instances of correlated growths to which I am about to refer, 

 and which from the dissection I shall describe I hope to elucidate, 

 differ from those classed under the head of Complemental Nutrition, 

 in that both growths draw with equal right and to an equal extent 

 upon the same store of nutriment. To the same stock of alimentary 

 matters they stand in the same relation ; they share and share alike 

 either as joint consumers or joint elaborators of it. If we may 

 coin a word from but second-hand Greek, and borrow one half of 

 our composite from our Anglicised word ' tautologous,' we would 

 call these growths ' tautogeneous.' As just hinted, they admit of 

 a twofold rationale. The blood either needs, as in the case I shall 



1 'Lectures on Surgical Pathology,' vol. i. lect. ii, 1853, by Mr. Paget, now Sir 

 James Paget. 



