130 FUNGI. 



those which influence the dispersion of the minute sporidia from 

 the terminal cysts. Probably they are more perennial in their 

 character, and are assimilated more to the oogonia of Cystopus 

 and Peronospata, being rather of the nature of resting spores, 

 inasmuch as the same threads usually bear the terminal fruits. 



Thecaspokes is a term which may be applied generally to all 

 sporidia produced in asci, but these are in turn so innumerable 

 and variable that it will, be necessary to treat of some of the 

 groups individually. The Thecaspores, for instance, of the Tu- 

 beracei offer several features whereby they may be distinguished 

 from other thecaspores. The asci in which these sporidia are 

 generated mostly partake of a broadly saccate, ovate form. The 

 number of sporidia contained in an individual ascus is usually 

 less than in the majority of the Ascomycetes, and the sporidia 

 approximate more nearly to the globose form. Usually, also, 

 they are comparatively large. Many have been figured by 

 Corda* and Tulasne.t Three types of spores may be said to 

 prevail in the Tuberacei : the smooth spored, 

 the warted or spinulose, and the areolate. The 

 first of these may be represented by the Ste- 

 phensia bombycina, in which the globose 

 sporidia are quite smooth and colourless. 

 Fig. 64.— Spondium of The warted sporidia may be observed in 



Genea verrucosa. ~ ... . -, . m ■. 



G-enea verrucosa, the spinulose m Tuber 

 nitidum, and the areolate are present in Tuber cestivum and 

 Tuber excavatum, in which the epispore is divided into polygonal 

 alveoli, bounded by thin, membranaceous, pro- 

 minent partitions. This form of sporidium is 

 very beautiful. In all no special provision is 

 made for the dissemination of the sporidia, 

 as, from their subterranean habit, none would 

 be available save the ultimate dissolution 

 Fig. 65.— Alveolate of the external integuments. As they are 

 sporidium of Tuber g^^y devoured by several animals, it is 

 possible hat they may be dispersed through the excrements. 



* Corda, "Ioones Fungorum," vol. vi. Prague. 

 t Tulasne, "FuDgi Hypogsei." Paris. 



