FR UCTIFICA TIONS 



9 



the Basidiomycetes) as soon as conditions of nutrition suffice. A limita- 

 tion exists only in so far as the isolated sporophores usually occur earlier 

 than the corresponding fructification. Where several spore forms occur 

 in the same species, it is called polymorphic. 



Another group of spore forms is not primarily dependent for its 

 initiation on the conditions of nutrition but on the rhythm of the change 

 of nuclear condition: either because their formation follows fertilization 

 or because meiosis generally takes place in the sporophore. In the first 



Fig. 7. — Coremia. 1. Stysanus thyrsoideas. 2. Acaulium nigrum. 



after Sopp, 1912.) 



(1 X 220; 2 X 40; 



case, they are connected with the beginning, in the latter with the end 

 of the diploid phase. 



In the first case they are recognizable morphologically since they show 

 encysted zygotes (the products of the sexual act) ; biologically they usu- 

 ally develop as hypnospores. According to the morphological position of 

 the cells which copulate, their morphological significance and name 

 varies, as we shall see in individual cases. 



In the second case, they are morphologically recognizable since they 

 form tetracytes (as daughter cells of gonotoconts). Apparently, since 



