PHYLOGENY 77 



(in Gorallina) an arrangement of four superposed cells as in the 

 " basidium " of the Uredinales. Moreover in one of the groups 

 of the latter, the Coleosporiacese, as well as in Ghrysopsora, this 

 division into four cells takes place within the spore-mother-cell, 

 not outside it. It is a reasonable tentative hypothesis that 

 this " internal " formation of the four cells is the primitive 

 mode, inherited from the predecessors of the groups, and that 

 the formation of an external " basidium " is a later adaptation 

 of their successors to their environment. This would lead one 

 to look for the ancestors of the Uredinales among the Red 

 Algse. 



The obvious implication is that the Coleosporiacese retain 

 much of the Uredinal primitive character, and this is borne out 

 by the fact that the ascidial host of Coleosporium is in every 

 case, so far as known, a species of Pinus. The teleutospore- 

 host may belong to the Composite or various other families, it 

 is true, but it is now generally admitted that the aecidial host 

 is the primitive, and that the others have been adopted by 

 successive mutations. It has an important bearing on this 

 argument that, in Gallowaya Pini, the teleutospores which are 

 of exactly the same nature as in Coleosporium are borne on 

 a Pine (Pinus inops Ait.). 



Again, it has been shown that it is possible, without violence, 

 to interpret the female-cells of the secidium as furnished with 

 a trichogyne, such as the carpogonia of the Floridea? possess, 

 though in the Uredinales (possibly as a consequence of their 

 terrestrial habit) it has become abortive. Trichogynes are not 

 uncommon in other groups of Fungi — in certain Ascomycetes, 

 in the Laboulbeniacese, and among the Lichens, in Collegia and 

 other genera. Moreover in Collema the trichogyne and corre- 

 lative spermatia are almost certainly functional (Bachmann, 

 1912); the same is true in the Laboulbeniacere, but in most 

 Ascomycetes the trichogyne has either been lost altogether, or 

 if it survives has lost its function. 



In order that the trichogynes in the ancestral Uredinales 

 should be effective, the female gametes must have been situated 

 beneath a stoma. It is a suggestive fact that in certain of the 

 group, belonging to the lowest forms, the sori of various kinds 



