316 THE BEGINNINGS OF CAUSAL MORPHOLOGY 



Duthiers put forward in his introduction a powerful plea for 

 the use of the experimental method in zoology. 



In some ways more directly connected with Enti^ick- 

 lungsmechanik was His's attempt in iS/4 1 to explain on 

 mechanical principles the formation of certain of the 

 embryonic organs by the bendings and foldings of tubes or 

 plates of cells. " His compared the various layers of the 

 chick embryo to elastic plates and tubes ; out of these he 

 suggested that some of the principal organs might be 

 moulded by mere local inequalities of growth the ventricles 

 of the brain, for instance, the alimentary canal, the heart 

 and he further succeeded in imitating the formation of these 

 organs by folding, pinching, and cutting india-rubber tubes 

 and plates in various ways." : 



But Roux was undoubtedly the first to make a systematic 

 survey of the problems to be solved and to work out an 

 organised method of attack. His earliest work deals with 

 the important problem of functional adaptation its 

 importance to the organism, and its possible mechanistic 

 explanation. The first paper 3 was a study of the branching 

 and distribution of the arteries in the human body (1878), 

 and a second paper on the same subject followed in iS/9. 4 



In these papers Roux showed how the development of 

 the blood-vascular system was largely determined by direct 

 adaptation to functional requirements, and he inferred the 

 existence in the vascular tissues of certain vital properties, in 

 virtue of which the functional adaptation of the blood-vessels 

 came about. Thus the intima or inner lining must possess 

 the faculty of so reacting to the friction set up by the blood - 

 current as to oppose the least possible resistance to its flow ; 

 the muscular coats must react to increased pressure by 

 growing thicker, and so on. 



These papers were followed in iSSi by his well-known 



1 Unsere /\'<>rf>i-rf<-//i nnd <i 'is f>/iyxi!(>^isi-/ie Problem Hirer 

 Entxtclnuiy^ Leipzig, 1874. 



: J. \V. Jenkinson, /',".i/w/w<y/A// /1in/>ryt>l<w, p. 3, Oxford, 1909. 



" I'rlx-r die VerzweigUllgen der I'lut-cf.^sc drs Mcnschen, "///;. 

 /.cit., xii., 1X78. 



1 "Ucbcr die IJedeututi^ dcr Alilciikim^ dcs Arterienstammes bci 

 der As-.-di-.d)c," J<n. /.<{(., xui., 1X79. 



