114 M. C. Montague's Organographic and Physiologic 



or membranous. In certain genera it is inverted elastically, in order 

 to shoot out the sporangia ie. g. Sjihcsrobolus). 



The receptacle is entire, and opens at the summit by a circular 

 or toothed orifice ; or it is truncate or dimidiate, and closed by a 

 thin membrane called epiphragma, which bursts to make way for the 

 sporangia {e. g. Cyathus) . These at first swim in a more or less 

 consistent mucilage which at length disappears. They are free or 

 fixed to the peridium, sometimes laterally, sometimes by the centre, 

 by means of a sort of cord. Their consistence is sometimes hard 

 and firm, sometimes more tender. The sporidia which they contain 

 are of a variable colour, and generally collected in the centre. These 

 fungi grow in autumn, and are, as far as is known, of no use. Their 

 morphosis, which has not been followed, demands the attention of 

 mycologists favourably situated for such observations. 



The Tuber acea; form an important tribe, whether on account of 

 their structure, so well explained by Vittadini, or their use for food. 

 The species have a single or double peridium. This peridium, when 

 single, or the internal, when there are two, is folded more or less 

 deeply into the interior of the fungus, so as to form veins of diff^erent 

 colours, giving it a mottled appearance. The sinuosities formed by 

 the folds of the peridium, which Vittadini has well compared to 

 those of the brain, do not proceed always from every point of the 

 circumference, as in the genus Genea (Vitt. Mon. Tub. t. ii. f. 7.) ; 

 more frequently, in the root-bearing species, the folds radiate towards 

 the summit from the point which is in contact with the soil ; in 

 some cases it is from the centre that they diverge. The outer pe- 

 ridium, which is wanting in the curious genus Gautiera, is frequently 

 floccose or byssoid. In the species with a tuberculated bark, this is 

 formed of very small and crowded elliptic cells. These cells, ac- 

 cording to Vittadini, serve in the Trufi[ies for the absorption of the 

 juices necessary for their growth, and perform consequently the 

 functions of roots. The flesh of TuheracecB, especially remarkable 

 for its veins, is of a different colour in different species. Its consist- 

 ence and hardness increase with age, which is the reverse of what 

 takes place in Ly coper dacea. We see at once the analogy which 

 closely -binds certain genera of this order with Hymenomycetes, and 

 others with Discomycetes. Gautiera graveolcns is indeed very near 

 to the Morells, and Genea is an introverted Helvetia. In both cases, 

 the organs of fructification, being disposed in an inverse manner, do 

 not receive the action of the air and light till after their dispersion. 



It would take too long time to review the forms which the peri- 

 dium assumes in the very numerous genera of this tribe; it is 

 enough, after the Italian monograph, to have indicated the origin of 

 these inner veins, which wise and provident nature has employed to 

 multiply the points of the fructifying surface without increasing too 

 much the volume of the plant. 



If we examine the parenchyme of Tuheracece, we recognise besides 

 that it is composed of cells differently fashioned, but in general 

 rather rounded than elongated. Between these cells, we observe 

 from space to space cavities very variable in their form. The one. 



