440 



I. 



The Podetium of Cladonia.* 



This paper is in reality a criticism of Krabbe'sf monograph of 

 the genus Cladonia. Krabbe maintains that the podetia belong 

 to and are a part of the spore-bearing organs (apothecia). His 

 conclusions are based upon the observation of the morphological 

 characters and the mode of development which, according to Reinke 

 and other modern biologists, are not sufficient. Nor can the mor- 

 phological characters or structure be deduced from its develop- 

 ment. Krabbe assumes that since the podetia of Cladonia origi- 

 nate in a manner similar to the apothecia of Ravialina, Parmelia, 

 Lecanora, etc., they must be apothecial structures The entire 

 discussion depends upon the points of view. Krabbe, having con- 

 sidered the podetia from the morphological and developmental 

 pointof view, naturally comes to different conclusions from Reinke, 

 who views the same structures from the physiological standpoint. 

 It is an excellent example illustrating the necessity of combining 

 morphology and physiology. Reinke very aptly states that if we 

 allow morphology and development to dominate our investiga- 

 tions we may come to the absurd conclusion that the floral 

 leaves are foliage-leaves and, vice versa, that the foliage-leaves are 

 floral leaves. Extending the illustration we might conclude that 

 mosses are liverworts, and that fungi are algae, etc. Reinke be- 

 lieves that the development of an organ should be represented as 

 describing a curve which extends from the beginning to the point 

 of maximum development of that organ. All intermediary stages 

 of development are to be considered, but the special importance is 

 to be attached to the fully developed structure. According to this 

 view thallus, foliage-leaf, thorn, tendril, sepal, petal, stamen, pistil, 

 should be represented as terminating at different points of the 

 curve. With these and similar introductory considerations, the 

 author finally enters upon the discussion of the podetia of Cla- 

 donia. 



* Reinke, J. Abliandlungen uber Flechten. I. Das Podetium von Caldonia. 

 Pringsheim's Jahrbiicher, 26 : 495-523. 1894. 



\ Krabbe, G. Entwickelungsgeschichte und Morphologie der polymorphen Flech- 

 tengattung Caldonia. Ein Beitrag zur Kenntniss der Ascomyceten. Leipzig (A, Fe- 

 lix). 1891. 



