88 



persistently dcinandcd an explanation. 

 Long dela\cd though this was, it 

 seemed at last to have been completely 

 and triumphantly provided by the 

 theoH' of e\olution. What could be 

 more obvious than that all this diver- 

 sity of form was the result of evolu- 

 tionar}' divergence? What more certain 

 than that structural homology was due 

 to common ancestry? Under the tre- 

 mendous impact of this new idea it 

 was inevitable that students of organic 

 form should regard as their primary 

 task a careful 'description of the ex- 

 ternal and internal structure of plants 

 and animals so that by diligent com- 

 parison of a wide range of tvpes the 

 evolutionary' histon' of the organic 

 world could be reconstructed. In the 

 period of its greatest expansion mor- 

 phology thus became preoccupied with 

 phylogcny to the exclusion of almost 

 everything else, and this priman' in- 

 terest has largely persisted to the pres- 

 ent time. 



With all these influences at work it 

 is therefore not surprising that the 

 purely descriptive and historical phases 

 of their work have attracted the chief 

 attention of most of those whose major 

 interest is with the studv of organic 

 form. The results of this studv have 

 been of vcr\' great significance in the 

 development of biology, and the writer 

 has no wish to disparage them in any 

 way or to belittle the contribution 

 which they have made and will con- 

 tinue to make toward our understand- 

 ing of living things. Nevertheless, if the 

 argument developed in the present 

 paper is sound, the dynamic aspect of 

 the problem of form is of far greater 

 ultimate significance than its descrip- 

 tive side alone. Morpholog\' should 

 concern itself with causes as well as 

 with results, and should not abandon 

 this most promising, though most difh- 

 cult, part of its territor}' to be explored 

 by ph)siology, genetics, biochemistr)' 



ANATOMY AND MORPIIOLOCY 



and other sister sciences whose main in- 

 terests lie elsewhere. 



To all this it may be objected that 

 names are unimportant; that whether 

 those who attack the dynamic aspect 

 of form call themselves morphologists 

 or cytologists or biophysicists is quite 

 immaterial, for no morphological caste 

 or guild can claim precedence for itself 

 here. Of course this is true, but as a 

 practical matter it should not be for- 

 gotten that the material which pre- 

 sents itself to the student of mor- 

 phogenesis is complex and requires a 

 rather special knowledge on the part 

 of the investigator if he is to be safe 

 from error and waste of effort. An out- 

 sider is notoriously prone to make 

 absurd mistakes if he works in a field 

 which is not his own by experience and 

 training, and nowhere is this more 

 true than in problems involving the 

 data of morpholog)'. One who is well 

 trained in this field has a ver\' real ad- 

 vantage in morphogenetic studies. 



But the morphologist may object 

 again that by temperament and train- 

 ing he is unfit to undertake problems 

 involving the dynamic side of his sub- 

 ject, since these require an approach 

 through experiment and the methods 

 of the physical sciences, with which he 

 is often unfamiliar and uns\mpathetic. 

 As he cannot thus be of real ser\ice 

 here, he may ask, why not leave him in 

 the ivory tower of his phylogenies and 

 his life histories and turn over to the 

 physiologists and their allies, fortified 

 by a little better morphological train- 

 ing, the whole troublesome task of de- 

 termining the causes of form? 



Such a defeatist attitude, it seems 

 to me, is based on the erroneous as- 

 sumption, often made by both mor- 

 phologists and non-morphologists, that 

 the only way to attack the problems of 

 morphogenesis is by experiment, in- 

 volving almost immediately the tech- 

 niques of the physical sciences. No one, 



