10 ON UNDERGROUND FUNGI. 



There is a third group to which Ave shall have to advert pre- 

 sently. As, however, the true truffles of commerce are the objects of 

 most importance in an economical point of view, I shall advert to 

 these first. 



The common Truffle, whether under that name we include 

 the French Truffle* (Tuber melanonporum), the black-seeded Truffle, or 

 our own most abundant species Tuber cestiviim, the summer Truffle, 

 presents when divided vertically a number of pallid veins which 

 communicate with the warty surface of a dark brown or black 

 tint, and consist of branched threads, which answer to the hymenium 

 (fructifying surface) of the cup-fungi, as they give rise to the fertile 

 threads which are terminated by the seed-sacs. A common lens is 

 sufficient to indicate their presence, where they appear as dark specks. 

 The further investigation requires a compound microscope, and few 

 objects are more interesting than the enclosed sporidia, of some of the 

 more marked of which I have submitted figures to the meeting. They 

 are in general of a comparatively large size, and their external surface 

 is variously spinulose, warty, or reticulated, often to an extent which 

 does not take place in more aerial Fungi. In a few cases, how- 

 ever, as in Balmvua, they are smaller and quite even. Very little is 

 known about the impregnation of Fungi, but in the true Truffles, as in 

 some species of the cup-fungi and the water-fungi, which are the 

 destruction of fish, and especially of young salmon, certain threads 

 swell at the tips and curl round the sacs, to which they impart the 

 male element, the whole process in Truffles being completed beneath 

 the surface of the earth. Spermatozoids or spermatia have not been 

 discovered in these Fungi. 



Several species have been found in this country, each of which is 

 distinguished by its own peculiar odour ; but most of these are so small 

 that they are at once thrown aside by the collectors. The odour of 

 Tuber melanoaporum is so penetrating that it cannot escape the prying 

 nose of the exciseman or douanier, however cunningly it may be 

 concealed. 



There is, however, a distinct genus Choiromyces, known amongst 

 other peculiarities by its pale colour and even surface and globose 

 sporidia, which is esculent, though far inferior to the summer Truffle. 

 The species sometimes grow to a large size, and are met with unexpec- 

 tedly in the most unlikely spots, but occur occasionally in great pro- 

 fusion, principally in avenues of oaks. We are not aware, however, that 

 they ever appear in our naarkets, and when fresh they are rather acrid. 

 Either the same genus, or one closely allied, produces in Africa and 

 near Damascus abundance of esculent Fungi, of which I have received a 

 large bag of dried specimens, which proved when cooked perfectly insipid. 

 They occur principally about the roots of several species of Cistus, 

 and are found again in the Canaries. They are quite worthless as far 

 as aroma is concerned. The CJwiromijces, or white Truffles, have long 



* We believe that the tiutfle collectors at Auclley End call young Tuber 

 centivum before the seed-sacs are formed by that nanip. 



