SOS THE MICROSCOPE. 



"We cannot conclude this "brief notice of the fungi with- 

 out adding a few words u2:)on that curious group of subter- 

 ranean plants, which instead of producing their spores at 

 the summit of a basidium, or extremity of a simple filament, 

 produces them in the interior of a vesicle or pouch, called 

 a theca or ascus. Of this sj^ecies the best known example 

 is the truffle [Tuber cihaj^ium). 



It is, perhaps, not very generally known that the 

 curiously formed, irregular mass, so much esteemed for its 

 delicious taste, and sought after as a luxury, the truffle, is 

 in truth a species of mushroom ; more properly speaking, a 

 subterranean puff-ball, or fungus. Its existence, entirely 

 I'cmoved from the action of light, is an anomaly even 

 among plants of the fungus kind ; for light, although not 

 in a large degree necessary to the fungus, is almost 

 always indispensable to its full development. It would^ 

 therefore, be most difficult to discover, if it were not for 

 a peculiar and j^enetrating odour, which dogs are taught 

 to recognise ; and by the aid of these useful animals its 

 presence is detected hidden beneath the soiL 



Tulasne and others have pointed out that these fungi 

 })resGnt two essentially different types. In the one, IIij- 

 menogastrcce, the internal fleshy mass presents a number of 

 irregular cavities, lined by a membrane analogous to that 

 which clothes the gills of the Agaric, and the superficial 

 cells produce at their free extremities three or four spores, 

 or seeds, which become detached, and eventually fill up 

 the cavities. The other type, Elaphemycoe, Tuheraceos, 

 comprising those of the truifle kind, and as may be sur- 

 jnised by the scientific name assigned to them — Tuber 

 ^'ibarium, — are plants characterised from the underground 

 ]'oot presenting a fleshy mass, the outer surface of Avhicli 

 constitutes the common envelope, 2)eridiu7)i, while the 

 jiumerous narrow sinuous cavities are lined and in part 

 idled up by filamentous tissue, mingled with cells of a 

 2)eculiar form, and terminating in spores. 



A section from the fleshy-looking mass cut very thin 

 (Plate I. No. 2), and viewed under a power of 250 

 diameters, is found to be chiefly comjiosed of cellular 

 substance, the interspaces of which are filled up by 

 jointed filaments, homologous to the mycelium or spawn 



