126 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



fructifications are ever formed. Clear instances of this are seen in Ulota phyllantha 

 and especially in Barbula papillosa among the Mosses, and in Allium sativum and 

 some other species among the Angiosperms 1 . In these cases also it cannot be shown 

 that the species has less than the usual power of maintaining its existence. The 

 names show that we are dealing with species whose nearest congeners go through the 

 complete normal course of development which includes the formation of fructifications, 

 and it may be proved, as has been done in another place, that in the former species 

 the fructificative members of the course of development have been excluded and have 

 disappeared in the progress of the phylogenetic evolution, and that the species 

 themselves therefore are in a reduced state owing to the loss of the most highly 

 differentiated stages of the development. Homologies with allied and perfectly 

 differentiated species may be followed for a certain distance, and then the homology 

 breaks off, is interrupted and is not restored; the course of the development 

 as a whole has become different from that of the type. 



This interruption of the homologies and the above-mentioned restitution of them 

 occur only in isolated species among the higher forms. If other species following the 

 same general plan of development were to be produced phylogenetically from them, 

 they would form secondary series in the vegetable kingdom which would diverge from 

 the main series and not fit into it. It is possible that such secondary series do exist 

 among the lower groups of plants which are not Fungi, but this is not yet certainly 

 ascertained. It was hinted above that we must assume the existence of such forms 

 among the Fungi, and proof of this necessity will be given in future sections. 



The points of view explained in the foregoing paragraphs will enable us to under- 

 stand fully the phenomena known as the alternation of generations in the vegetable 

 kingdom. Other facts and other points of view may have to be considered in 

 reference to some of the similar phenomena which occur in the animal kingdom, but 

 we cannot discuss them here. Views differing from those here expressed, and as it 

 seems to me unnecessarily complicated, have been advanced on more than one 

 occasion. On this point the reader is referred to Pringsheim and other writers 2 . 



SECTION XXXIV. The general phenomena to which attention has been called 

 in the preceding pages recur everywhere in the Fungi also, that is to say, the 

 phenomena observed in the Fungi are only special cases of phenomena which are of 

 general occurrence in the vegetable kingdom, and the Fungi from the purely 

 morphological point of view are ' like any other plants.' This has gradually come 

 to be understood since Tulasne's work of reformation mentioned above. He himself 

 could not possibly have a clear view from the first of the meaning and application of 

 his discoveries in every direction. He therefore named the phenomenon which he 

 had discovered the pleomorphy or pleomorphism of the Fungi, especially of their 

 reproductive forms, and as these expressions clearly indicate the discovered facts and 

 do not go beyond them, they were good and correct at the time and are so still if we 

 are speaking of that which Tulasne was discussing. If they have ever given rise to 

 misapprehensions, it has not been the fault of their author, but of those who did not 

 understand them. 



1 See Bot. Ztg. 1878, p. 481. 



3 See Pringsheim, Ueber d. Generationswechsel d. Thallophyten (Monatsber. d. Berliner Acad 

 Dec. 1876), and the literature there cited. 



