4 PREFACE. 



accumulated, and is here summarized, as to their presence in other types, 

 must be regarded as establishing the fact that the ascocarp originates in 

 a sexual apparatus. Objections which are still urged by the opponents 

 of De Bary's views are rather in the nature of complaints and denials 

 than in the presentation of new facts. 



A most fertile source of confusion in the discussion of the relation- 

 ships of fruit forms in the fungi has been the failure to make all com- 

 parisons from the standpoint of a strictly phylogenetic morphology. 

 Whatever excuse there may be for introducing physiological concep- 

 tions into the formal classification of tissues in the higher plants, there 

 can be no question that great confusion has arisen in the morphology 

 of the fungi and algse from allowing considerations of functional 

 equivalence or difference to mingle with and modify the conceptions 

 of what should be a strictly phylogenetic morphology. It may be a 

 hopeless task — it certainly is not at present a very important or stim- 

 ulating one — to attempt to determine with exactness lines of phylogenetic 

 descent among such plastic forms as the algae and fungi; but no other 

 or lesser aim than this should be allowed to masquerade under the guise 

 of morphology. Physiological data as to the functions and mechanics 

 of cells and organisms are of far greater biological significance than 

 those of phylogenetic morphology, but this is no reason for mixing the 

 two or allowing such attempts as we may make at the arrangement of 

 plant forms in evolutionary series to be vitiated by the introduction of 

 purely functional criteria into the determination of our morphological 

 classifications. The question, for example, whether a given organ is 

 functional in its more primitive or in some modified fashion can have no 

 bearing upon the determination of its morphological nature or rela- 

 tionships. 



Comparisons must frequently be made and hypothetical morpho- 

 logical categories established on data which are incomplete and can, 

 perhaps, never be made complete, but a lack of data as to phylogenetic 

 relationship can never be compensated for by evidence of functional 

 equivalence or non-equivalence. The modern fields of causal and 

 experimental morphology, developmental mechanics, etc., belong with 

 the physiological rather than the morphological disciplines, and their 

 results have the same bearing upon the classifications of phylogenetic 

 morphology as have other physiological data. If there can be agree- 

 ment that the various developmental stages and fruit forms of the fungi 

 and alg^ shall be classified and named in accordance with what can be 

 determined as to their phylogeny a number of disputed questions will 

 disappear. 



