194 INTRODUCTION TO THE STUDY OF FUNGI 



thus bringing in a certain portion of wood as Truffle grounds 

 each year. At Bouardeline, for instance, the annual return 

 from Truffles in a plantation of less than half an acre was from 

 £4 to £5. Another case is adduced in the arrondissement of 

 Apt, where several proprietors have made plantations ; the 

 trees are left about five or six yards apart, and so soon as their 

 branches meet, and shade the ground too much, they are thinned 

 out." 1 



There are several other genera of Tuberaceous Fungi, but 

 of little or no commercial importance. The species of 

 Hydnotrya (Fig. 81) have long twisting 

 cavities in the interior, and the sporidia 

 are globose and warted. In Hydno- 

 holites the sporidia are globose and 

 -r. or rr 7 . rr i ■ alvcoktc (Fig. 82). In Choiromyces 



FiG.Sl.— Hydnotrya Tidasnei. \ b / a 



the sporidia are also globose, covered 

 with blunt spines. These Tubers sometimes attain to the size 

 of a man's fist. The African Truffle is Tcrfezia leonis, which 

 was discovered about four hundred years ago. For ages Truffles 

 have been eaten by the natives, but a peculiar interest attaches 

 to this species from the fact that the 

 French Academy of Sciences recently 

 discussed them ; and it is probably this 

 species of which it is said that they can 

 be imported from Bagdad and Biskra 

 so that they can be sold in the markets ^i^- ^'^•-Hydnohoiitcs with 

 of Paris at about one penny per pound. 



This is possibly an exaggeration, but at six times the price 

 they would have some influence on tlie Truffle trade. One 

 species is reported to realise twelve shillings a pound in 

 Italy, but what a comparison ! 



In the genus Sphacrosoma the hymenium soon becomes 

 exposed (Fig. 83), the elongated cells or asci are closely packed 

 together side by side, as in the species of Pcziza ; so that the 

 genus approaches the character of a subterranean Discomycete, 

 as also does another genus named Hydnocystis. Indeed, it is 

 difficult to distinguish this genus from Bcrggrcnia, which is 



^ C. E. Broome in Juurn. Roy. Ilort. Society, and in Gardener's Clironicle, 21st 

 Oct, 1865. 



