B2 PHYLOGENY 



Pyronema confluens and in many other members of the Asco- 



inycetes there is a double fusion (one in the ascogonium and 

 one in the young ascus), followed by a double reduction in the 

 ascus during t ho format ion of the eight spores, the first division 



being meiotic, I he sec ! homotypic, anil the third brachymeiotic. 



In view of the established relationship between the Ascomycetes 

 on the one hand and the Uredinales and Basidiomycetes on 

 the other, this idea seems to be very unlikely. If correct, the 

 double process is a special development, peculiar to some only 

 of the Ascomycetes. The matter can only be decided by fresh 

 investigations, but it seems in all probability that the hype- 

 thesis of a second fusion and subsequent brachymeiosis is the 

 result merely of a misinterpretation of the observed phenomena. 



According to Lutman (1910). in the Ustilaginales most of 

 the cells of the mycelium are binucleate,but the perfect resting 

 spores are always uninucleate, as are the cells of the basidia. 



Rawitscher (1912) says the same, and adds that the con- 

 jugate condition arises (according to the species) by the 

 anastomosis in pairs either of the basidium-cells, or of the 

 basidiospores, or of the cells of the mycelium produced by 

 them, and the passage of the nucleus of the one cell into the 

 other to form a synkaryon. 



Finally, it may be pointed out that the ideas embodied in 

 the foregoing discussion are in harmony with the now generally 

 accepted doctrine of the polyphyletic origin of the Fungi, by 

 which it is assumed that their various groups are not derived 

 from one or two ancestors, but originated separately from 

 distinct sub-divisions of the Alga?, much in the same way in 

 which (on a smaller scale) the non-chlorophyllose Phanerogams 

 have arisen from various orders or families of Flowering Plants. 

 From this point of view, according to which the vast majority 

 of the Fungi originated from the Red Alga-, it is not without 

 significance that already some of that group are known which 

 (though still rightly classed as Algse) have assumed a true holo- 

 parasitic habit — a statement which cannot be made to the same 

 extent, if at all, about other algal groups. Examples are found 

 in the well-known Harveyella mirabilis (Sturch, 1899) and in 

 Clioreocolax Polysiphoniae (Richards, 1891). 



