ON THE SEXUALITY OF THE FUNGI. 285 



and Pleospora.i la this series there is no place for the 

 composite Ascoraycetes and Lichens — for although the sexual 

 process by means of spermatia is only an adaptive form, the 

 difference is too great to fit into the main series. How then 

 do these forms abut on to the main series ? Has a sexual 

 process arisen in the Ascomycetes a second time ; or did these 

 forms branch off early, and evolve and specialise their peculiar 

 mode of fertilisation from the original type ? The first hypo, 

 thesis cannot be maintained; the second seems highly prob- 

 able. 



We must regard the separation of the sexual organs in the 

 composite Ascomycetes and Lichens as an adaptation, though 

 we cannot say how it came about or served the organisms con- 

 cerned. It is remarkable that this only occurs in forms which 

 develope a stroma. 



The composite Ascomycetes, therefore, branched off before 

 the sexual process was lost ; whether the Lichens came off at 

 the same time is not clear — the latter possibly form more than 

 one series, moreover. 



The Disco mycetes must also have branched off early from 

 the main series; they form a series in- the following forms, 

 gradually culminating in apogamy — Ascobolus furfur- 

 aceus, A. pulcherrimus, &c., Pyronema conflueus, 

 Peziza tuberosa, Fuckeliana, Willkommi (the latter 

 examined by Fisch). 



The Uredineae must also have come off very early from 

 forms in which sexuality still existed. 



As I understand the foregoing, the following scheme fairly 

 expresses the views ; it being borne in mind, however, that the 

 lines are not intended to indicate more than the general direc- 

 tions in which descent may be traced. Of course, such a 

 diagram suffers from being drawn on a plane surface. No 

 doubt more than one line should be drawn towards the 

 Lichens. 



' Zopf, 'Bot. Zeit.,' 1879, p. 73. Bauke, 'Bot. Zeit.,' 1879. 



