THE SEXUALITY OP THE FUNGI. 43 



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 1 ? The first hypothesis cannot be maintained ; the second 

 seems highly probable. 



We must regard the separation of the sexual organs in the compo- 

 site Ascomycetes and Lichens as adaptation, though we cannot say 

 how it came about or served the organisms concerned. It is remark- 

 able 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 Discomycetes must also have branched off early from the main 

 series ; they form a series in the following forms, gradually culminating 

 in apogamy — Ascobolus furfuraceus, A. pulcherrimus, &c, Pyronema 

 confluem, Peziza tuberosa, Fucheliana Willkommi (the latter examined 

 by Fisch). 



The Uredinese 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 in- 

 tended to indicate more than the general directions 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. 



