﻿43° BOTANICAL GAZETTE [june 



removal of the outer layer of the peridium exposes the origin of these 

 septa as a network of numerous anastomosing lines covering all parts 

 of the fungus except that immediately under the scar. In a section of 

 the fungus the septa appear as labyrinthiform anastomosing veins of a 

 dark translucent gray color, appearing in freshly cut specimens darker 

 than the hymenial layer. In specimens preserved in alcohol they 

 become white and are difficult to distinguish from the venae externae. 



The venae externae {y, ex, ^ fig. 2) appear in a section of the fungus 

 as branching veins of a pure white color, and of a cottony aspect under 

 the hand lens. They alternate with the darker septa, ending blindly 

 toward the periphery, but all communicate with a mass of similar 

 tissue which underlies the scar, and through it communicate with the 

 exterior. This mass of tissue is in places lined with a layer similar to 

 the inner peridial layer, but in other places it abuts directly upon the 

 hymenial tissue. In cases in which the scar is interrupted, the mass of 

 underlying tissue is likewise interrupted, and the venae externae 

 accordingly form more than one group. 



The hymenial layer is embraced between these two types of veins. 

 It is of a fleshy but somewhat granular texture, and of a violaceous 

 brown color. 



The septa are composed of densely interwoven hyphae having for 

 the most part a radial course, though strands of hyphae running in 

 other directions are not uncommon {syfig. 2, B). The venae externae 

 {v. ex,, fig. 2 J B) consist of more loosely intertwined hyphae. The 

 hymenial layer consists of closely packed asci interspersed with numer- 

 ous hyphae, and forming no definite palisade layer. The hyphae of 

 the venae externae and of the gleba are very large (4-1 o/x in diameter), 

 septate, and sparingly branched. The asci are difficult to see clearly 

 in a section, but may be easily seen in macerated material- They are 

 1-5-spored, but nearly all of them are 4-spored. The ascus is irregu- 

 larly elliptical, averaging 45 X 70/1 (p. sp.) and usually is furnished with 

 a long pedicel. Big. j, A shows the most common form of ascus, 

 but irregular asci like that shown in fig. j, B and Care not uncommon. 



The spores are large, elliptical, acutely echinulate, and of a slightly 

 violaceous brown color. Spores occurring in 4-spored asci measure 

 15-25 X 25-38^1, averaging 22X35/^^. The spores from one-and two- 

 spored asci are larger, in the former case reaching 31 X48/i'. 



As will be seen by this description the fungus belongs to the genus 

 T'^^^r (subgenus Aschion), and approaches very close to Tuber rufum 

 Pico, and to T. nitidiim Vittad. in general characteristics and micro- 



