BASIDIOMYCETES 



413 



siderably during their further development (they increase in breadth only 

 slightly) and, at maturity, project considerably above the hymenium. 

 The spindle of the first nuclear division (meiosis) is sometimes longitu- 

 dinal, more often oblique (Fig. 271, 2). The spindles of the second 

 nuclear division are situated at unequal heights and are more or less 

 longitudinal. The diploid nucleus generally passes through three steps 

 of division, so that the young basidium is eight nucleate. This special 

 type, within which are placed longitudinal or oblique nuclear spindles, 

 where the basidia are cylindrical or variable in form, is designated as the 

 stichobasidial type. The example given here, the Cantharettus basidium, 

 is, consequently, a stichobasidial holobasidium or, more briefly, a sticho- 

 basidium (Fig. 265, 7 to 12). The young basidium becomes clavate, 



Fig. 271. — Cantharettus cibarius. Development of basidia. (X 1,20U; after Juel, 1917.) 



lengthens only slightly and is very constant in form. The spindles of all 

 nuclear divisions lie approximately at the same height and near the tip, 

 mostly directly under it, and crosswise. This second type of holobasidium, 

 which is distinguished by the constant clavate form of basidia and by the 

 apical nuclear spindles placed crosswise at the same level, is called the 

 chiastobasidial type and the resulting basidium, chiastobasidium. 



These two developmental types of holobasidium, the sticho- and 

 chiastobasidium, are notable, even in a group in which they appear beside 

 each other, in possessing no transitional forms. In the cases in which it is 

 believed that transitional forms have been found, e.g., Boletus (Levine 

 1913) the published figures, 58, 62 and 77, may easily be explained by the 

 sections being cut in an oblique plane. 1 



1 This summary dismissal of Levine's figures does not apply to Exobasidium 

 Rhododendri (Eftimiu and Kharbush, 1927), where figures 32 and 34 show respectively 

 a sticho- and a chiastobasidium, or figure 36 where two spindles are transverse and one 

 is longitudinal. The same is shown in figures 5 and 5' in E. discoideum. This con- 

 vincing evidence of the absurdity of recognizing the Cantharellales as a separate 

 order was received after this book was in press, too late to make such radical changes 

 as the suppression of the Cantharellales would make necessary. 



