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PART IV. VEGETABLE TAXONOMY. 



from two to four spores, which are set free by the decay of the 

 surrounding parts. Sexual organs are not known in these Fungi, 

 nor has the mode of germination of the spores been observed. 

 The most prized of the edible species are Tuber sestivum and 

 Tuber melanosporum. 



Fig. 514. — Eurotium repens. A, branch of mycelium bearing conidia, c, and young 

 archicarps, as; B, spirally twisted archicarp as, with the antheridial branch />, and an 

 envelope branch ; C, older specimen with more envelope branches, and ./*, antheridial 

 branch ; D, young sporocarp seen from without. K and F, other sporocarps in longi- 

 tudinal section ; G, ascus with spores. A, magnified 190 diameters, the rest about 600 

 diameters. After De Bary. 



The Pryrenomycetes are characterized by producing long 

 club-shaped asci in the interior of a roundish or flask-shaped 

 receptacle or perithecium. The latter may occur singly, or many 

 may be aggregated together on a common organ called a stroma. 

 The group includes a number of genera, among them Diatrype, 

 whose fructification forms black, warty-looking prominences 



