DEVELOPMENT OF MORPHOLOGICAL CONCEPTIONS 5 



garded as roots, stems, or leaves under various disguises. It does not 

 seem unreasonable to characterize this conception as the arbitrary 

 selection of an ideal type, the natural offspring of the conception of 

 ideal types that prevailed in taxonomy. In other words, morphology 

 was dominated by taxonomy, and morphologists were first and 

 chiefly taxonomists. It is this phase of morphology that must con- 

 tinue to be exploited chiefly by taxonomists, and which still remains 

 in those conservative schools in which instruction lags far behind 

 research. This doctrine of types resulted in the cataloguing of organs 

 just as species were being catalogued, and, although capable of re- 

 cording material, it was incapable of advancing knowledge. 



An accompaniment of this mental attitude was the explanation of 

 metamorphoses. It is almost impossible for one age to conceive of the 

 mental condition that was satisfied with the explanations of a previous 

 age. In this case it must be remembered that the earlier botanists 

 were either ecclesiastically trained or not trained at all, and to them 

 it was entirely satisfying to explain all metamorphoses upon teleo- 

 logical grounds. It is a matter of great surprise, however, to note how 

 this point of view is still maintained by some investigators who have 

 abandoned the doctrine of types, and in every other respect are inhal- 

 ing a modern atmosphere. 



One serious result of belief in the doctrine of types was the use of 

 the most complex structures to explain the simpler ones; the reading 

 of complexity into simplicity. For example, the type flower selected 

 was one that had become completely differentiated; in short, a highly 

 organized flower. This was read into all simpler flowers, and was even 

 carried over the boundary of angiosperms and applied among gymno- 

 sperms, to the utter confusion of terminology and understanding. 

 Fortunately for the students of cryptogams, a great gulf was thought 

 to be fixed between plants with seeds and those without, and this the 

 flower did not cross. 



It is safe to say that this phase of morphology, with its types and 

 teleology, and its use of complex structures to interpret simple ones, 

 is now in its decline. 



II. The Phase of the Structure of the Developing Organ 



This type of morphology has chiefly characterized the period under 

 consideration. Its fundamental conception is evolution; its purpose is 

 to discover phylogeny ; and its method is based upon the belief that 

 ontogeny recapitulates phylogeny. As a consequence, there was de- 

 veloped for the first time what may be called a philosophy of the plant 

 kingdom, organizing the details of morphology into one coherent whole 

 about such central facts as alternation of generations and heterospory. 

 Study of the metamorphoses of plant organs was replaced by a study 



