POLYMORPHISM. 193 



oval conidia which are solitary on the tips of the threads. 

 Therefore this Hypocrea will possess two different kinds of 

 conidia, as is the case in many species of Hypomyces. 



A most familiar instance of dualism will be found in Nectria 

 cinndbarina, of which the conidia form is one of the most common 

 of fungi, forming little reddish nodules on all kinds of dead 

 twigs.* 



Almost any small currant twig which has been lying on the 

 ground in a damp situation will afford an opportunity of studying 

 this phenomenon. The whole surface of the twig will be covered 

 from end to end with little bright pink prominences, bursting 

 through the bark at regular distances, scarcely a quarter of an 

 inch apart. Towards one end of the twig probably the pro- 

 minences will be of a deeper, richer colour, like 

 powdered cinnabar. The naked eye is sufficient 

 to detect some difference between the two kinds 

 of pustules, and where the two merge into each 

 other specks of cinnabar will be visible on the 

 pink projections. By removing the bark it will 

 be seen that the pink bodies have a sort of 

 paler stem, which spreads above into a somewhat 

 globose head, covered with a delicate mealy bloom. 

 At the base it penetrates to the inner bark, and 

 from it the threads of mycelium branch in all 

 directions, confined, however, to the bark, and 

 not entering the woody tissues beneath. The 

 head, placed under examination, will be found to 

 consist of delicate parallel threads compacted to- 

 gether to form the stem and head. Some of these 

 threads are simple, others are branched, bearing *>. t~7 wig 



1 & with Tuberculana 



here and there upon them delicate little bodies, on tin upper por- 



... TI -i , i T tion, A T ee*/-iaonthe 



which are readily detached, and which form the lower. 



mealy bloom which covers the surface. These are the conidia, 



little slender cylindrical bodies, rounded at the ends. 



Passing to the other bodies, which are of a deeper colour, it 



* "A Currant Twig, and Something on it," in "Gardener's Chronicle," 

 January 28, 1871. 



