34 



PRINCIPLES OF PLANT-TERATOLOGY. 



typed instance of this very abnormality, but more 

 complete and thorough. It is evidently a transitional 

 type, standing between the Agarics and the Poly- 

 poracese. Fries places it in the latter, while Leveille 

 claims it for the. former. 



Patouillard found in Psathyra gyroflexa that the gills 

 throughout the cap were split up into orbicular out- 

 growths slightly united together. Is this a reversion 

 towards the Hydnum condition ? W. G. Smith figures 

 an Agaricus aeruginosus in which the gills were reduced 

 to a regularly-arranged set of teeth, as in Hydnum ; 

 this, almost certainly, is a case of reversion. 



Polyporus is particularly liable to change of shape 

 of its fructification. The unilateral bracket-like cha- 

 racter is clearly derived from its habitat on the sides 

 of tree-trunks, etc. If grown on a horizontal sub- 

 stratum the cap may be centrally attached to the 

 stipe, as in Boletus, etc. Jacobasch observed incrusted 

 forms of .Poly porus, and transitions to these from the 

 normal forms. The incrusted is the normal condition 

 in the section Resupinati. 



Morot observed in Pleurotus ostreatus, an Agaric 

 which normally has a unilaterally-attached stipe, that 

 the cap was quite circular and regular, the gills hardly 

 decurrent, as in the normal case, and more like a 

 Glitocybe. 



6. FUSION. 



Cases of fusion are very common in Fungi, the 

 hyphal tissues lending themselves extremely readily 

 to this phenomenon. It is by no means always pos- 

 sible to distinguish between cases of fusion and of 

 forking. 



Lamotte describes the intimate union of the stipes 

 of two individuals, of which one penetrated the cap of 

 the other. 



W. Gr. Smith observed, in Geaster fornicatus, union 

 between the basal part of two plants forming together 

 a single large base. 



