32 MM. Tulasne on the Histonj of the Hijpogaous Fungi. 



The repeated examination of the structure of many of these 

 plants in different stages of growth, has conducted them to very 

 interesting results, throwing much light upon the life of subter- 

 ranean Fungi. 



It has long been known that in the ordinary Fungi, the fleshy 

 body, of such varied form, commonly considered as forming the 

 whole of the fungus, is only an external development, a tempo- 

 rary product, analogous to certain compound fruits, originating 

 from a filamentous, byssoid, irregular mass extending beneath 

 the surface of the soil or in the interior of the bodies supporting 

 these vegetables, comparable to the subterraneous stems of va- 

 rious plants ; this mass, called the mycelium or thallus, is what, 

 under the name of Mushroom spawn, is commonly used for the 

 reproduction of the Mushroom in beds. 



All Fungi when carefully examined presented this filamentous 

 mycelium, concealed before the fonnation and what may be 

 called the expansion of the Fungus ; the Truffles however seemed 

 to be devoid of it, and several authors, whose opinions had been 

 hastily received, had supposed that the Truffles were produced 

 directly from the spores of these plants, called by them truffi- 

 nelles, which became increased and dilated in all directions. 



Facts observed by Messrs. Tulasne in genera closely allied to 

 the Truffles had already rendered this view, altogether hypo- 

 thetical, inadmissible. Thus, in Balsamia, a genus very close to 

 the true Truffles, Messrs. Tulasne had observed the spores during 

 germination, emitting, like those of other Fungi, delicate ramified 

 filaments, which, by their interlacement, would form the myce- 

 lium, destined to reproduce, subsequently, new fleshy bodies, the 

 true fructification of these vegetables. In Delastria and Terfezia, 

 other genera of this tribe, and better still in the Elaphomyces, 

 which are a little removed, this mycelium reproducing the fleshy 

 body which constitutes the Fungus properly so-called, persists for 

 a long time around it, and by its presence proves that these sub- 

 terraneous Fungi, so near to the Truffles, do not difitr in this 

 respect from ordinary Fungi. 



It might therefore have been assumed with nearly perfect cer- 

 tainty, that the Truffles proper also possessed a mycelium, pro- 

 ducing these fleshy and fungous bodies, but quickly decaying 

 and allowing them to continue to grow in an isolated condition. 

 This has been actually demonstrated, in observations carefully 

 made by M. L. R. Tulasne in the Truffle grounds of Poitou, who 

 has seen the soil in which they grow traversed, in the course 

 of September, by numerous white, cylindrical filaments, much 

 finer than common sowing thread, yet themselves composed of 

 articulated microscopic filaments three to five thousandths of a 

 millimetre in diameter. These white threads arc continuous with 



