GOETHE'S PROGRESSIVE METAMORPHOSIS 159 



Plants alone are considered, or if sporangia are not regarded too scruputously 

 from an evolutionary point of view, and if it be assumed that they may 

 In- and have been habitually generated at large in the course of descent 

 upon pre-existent foliar organs. If these points be granted, then it might 

 be possible to retain Goethe's progressive Metamorphosis as the basis of 

 an evolutionary story applicable to the Higher Plants. As a matter of 

 fact, Botanists continued to analyse and describe the flowers of the Higher 

 Plants in this way for a whole generation after the Origin of Species 

 had been published. The flower was habitually regarded as the result 

 of metamorphosis of a foliage shoot. Though the point was not always 

 put into direct terms, the underlying assumption was that a conversion of 

 vegetative parts into propagative parts takes place in the individual : that 

 sporangia originated sporadically in descent, as they seem to do in certain 

 cases now, and that such changes as are seen in the development of 

 the individual had their place also in the history of its evolution. But 

 increasing knowledge of the life-cycles of the lower forms, and of their 

 comparison one with another, was meanwhile leading to sounder views of 

 the origin of the higher Vascular Plants. Alternation of generations 

 became gradually a more exact factor in the morphology of the last half- 

 century. It seems no longer possible to look upon the Vascular Plant as 

 a primary entity, as it was held to be in the time of Goethe. The 

 sporophyte generally, and consequently the plant-body of all the Higher 

 Plants which is a sporophyte, must necessarily be held to be secondary 

 by all those who recognise antithetic alternation as a constant feature in 

 descent of the Archegoniatae : for them the story of origin of the sporo- 

 phyte must affect the interpretation of its parts. 



A fundamental question of method in morphology is involved in this 

 discussion, viz. the question of the validity of conclusions based on 

 observations of the ontogeny as against the well-founded conclusions of 

 phylogeny. It will now be generally agreed that, provided the conclusions 

 as to phylogeny be sound, they should have the precedence over those 

 based on observation of the individual life. But in the practice of the 

 middle part of last century it was customary to act in the opposite sense, 

 and to take the successive events in the story of development of the 

 individual as the basis of morphological history : such views on descent 

 as are based on comparison were often left out of account or given only 

 a second place. If this latter principle be adopted, then conclusions 

 harmonising with Goethe's progressive metamorphosis will follow, and the 

 sporophyll may be accepted as an altered foliage leaf; but if precedence 

 be given to the results of a broad comparison, then a converse conclusion 

 will necessarily appear the more probable. 



But there is also another question involved in Goethe's view of " pro- 

 gressive metamorphosis," that of the origin of the sporangia which appear 

 in the strobilus or flower. The assumption that sporangia can be formed 

 indiscriminately upon pre-existent vegetative parts was at the back of 



