MM. Tulasne on the History of the Hypogceous Fungi. 23 



a byssoid, flocculent mycelium of the same nature, which enve- 

 lopes the young Truffles and forms immediately around them a 

 sort of white felt several millimetres thick, the filaments of which 

 are directly continuous with the external layer of the young 

 Truffle, scarcely so large as a nut at this epoch. In a short time 

 the gradual destruction of this byssoid envelope commences ; at 

 first a part, then the whole is lost, and the Truffle appears com- 

 pletely isolated in the soil. 



Thus, that which was indicated by analogy is confirmed by di- 

 rect observation, and it is seen that the Truffles, like the other 

 Fungi, are reproduced by spores which give origin to a fila- 

 mentous raycehum, the source of new Truffles. These facts, im- 

 portant in a scientific point of \iew, from the uniformity they 

 establish in the mode of existence of the whole of a large class of 

 vegetables, may, like many other scientific discoveries, one day 

 become a source of useful applications. 



These singular plants, thus isolated in the midst of the soil at 

 the epoch of their reproduction, without apparent external organs, 

 nevertheless exhibit internally a structure much more compli- 

 cated than was at first supposed. The observations of M. Vitta- 

 dini had already indicated the curious arrangement of the black 

 and white veins which traverse the tissue of the Truffles, and 

 these had been mentioned by the earliest observers; but the 

 more varied and more precise investigations of Messrs. Tulasne 

 have shown much more clearly their relations and destination. 

 When young, the Truffles exhibit very irregular sinuous cavities, 

 partly communicating with each other and terminating, some- 

 times at a single orifice corresponding to a depression or umbi- 

 licus on the outside, sometimes at several points of the surface 

 which present no distinguishable character externally. As they 

 advance in age, the partitions which separate the cavities become 

 thickened, the tissue composing their surface is developed into a 

 kind of white tomentum which obliterates them ; hence result 

 two systems of veins ; one set coloured, corresponding to the 

 partitions which separated the primitive cavities, the other white, 

 formed by the filamentous tissue which finally fills these cavities. 

 The foiTuer are continuous with the external tissue which 

 composes the envelope of the Fungus, or pei'idium; in their middle 

 portion they are formed of a network of filaments or elongated 

 cells, running in the direction of the cavities ; from this arise 

 shorter filaments, almost perpendicular to the first, and the in- 

 flated extremities of these become the sporangia, or sporigenous 

 cells ; the deep colour is due to the black or brown colour of the 

 spores. The other veins, the white ones, appear to be formed of 

 the prolongations of sterile filaments, intermingled with sporige- 

 nous cells, and originate like them from the primitive partitions. 



