168 



BOTANY 



eight in number, but may be much more numerous ; e.g. Streptotheca 

 Boudieri has thirty-two. The asci are closely set, and with the 

 paraphyses form a continuous hymenium lining the interior of the 

 usually cup-shaped, large spore-fruit. These are often very conspic- 

 uous and brilliantly colored yellow, orange, or scarlet. 



Sex-organs. The formation of the spore-fruit is usually purely vegetative, 

 but in a few instances, of which the best known is Pyronema confluens (Fig. 133), 

 there are well-developed sexual organs. These in Pyronema consist of a nearly 

 globular oogonium, having a curved tubular outgrowth, the conjugating tube, 

 which is later cut off by a basal wall from the body of the oogonium. The anther- 

 idium is a somewhat club-shaped body and fuses with the conjugating tube, into 

 which its contents pass. The basal wall of the conjugating tube next becomes 

 partially absorbed, and allows the contents of the antheridium to pass Over into 



FIG. 134. A, a Truffle (Tuber sestivum). (Natural size.) B, section of another 

 form, T. rufiim, showing the sporogenous region, sp. C, asci of T. rufum. (All 

 after TULASNE.) 



the body of the oogonium, where each antheridial nucleus fuses with one of those 

 in the oogonium, somewhat as in the compound fertilization in Albugo bliti. 



Fruit-body. From the fertilized oogonium filaments bud out, the ascogenous 

 hyphse, and upon these are later formed the asci. From the hyphse adjacent to 

 the oogonium numerous branches develop which grow in among the ascogenous 

 hyphse, and form the paraphyses which contain the pigment and give the fruit 

 its color. The subhymenial tissue and the outer tissues of the fruit also arise 

 from the sterile filaments. The asci produce eight spores in the manner already 

 described. 



Order V. Tuberineae 



Truffles. The Tuberineae, or Truffles, live for the most part en- 

 tirely underground. It is supposed that the mycelium in many of 

 them grows connected with the roots of various trees, forming the 

 so-called Mycorhiza, but the development of the group is imperfectly 



