414 COMPARATIVE MORPHOLOGY OF FUNGI 



Further development of the sticho- and chiastobasidia proceeds 

 similarly. In the next step, the daughter nuclei of the primary basidial 

 nucleus remain passive. Independently of the position of the nucleus, 

 the basidia form small protuberances equal to the number of the nuclei 

 which are usually differentiated into sterigmata and young spores (Fig. 

 265,12). Sometimes this process proceeds very rapidly; thus in the forms 

 with smooth, hyaline spores, there elapses 0.5 to 1.5 hours between the first 

 appearance of the spores on the ends of the sterigmata and the discharge 

 of these spores. In the form with thick-walled, colored spores, the time 

 is occasionally greater, in Coprinus sterquilinus, 32 hours; nevertheless, 

 even with the latter forms, the chief time for maturing, i.e., growth in size, 

 takes only V± to l\i hours (Buller, 1922). After the young spores are 

 already formed, the nuclei pass into them and they are ab jointed from the 

 mother cell. Spore formation is exogenous on the sterigmata (in con- 

 trast to the ascus), independent of the action of the nuclei. 



If the sterigmata are apical, the basidium is called acrosporous 

 (Tieghem, 1893). This insertion has been found for all chiastobasidia 

 and a large majority of stichobasidia. In Tulostoma (Fig. 369, c) the 

 sterigmata and spores are lateral, i.e., on the vertical sides of the basidia 

 and are, therefore, called pleurosporous. Thus, the stichobasidium is 

 divided into two types, an acrosporous or Cantharellus type and a pleuro- 

 sporous or Tulostoma type . The development of the pleurosporous sticho- 

 basidium is imperfectly known (as can be concluded from the single figure 

 of Tulostoma) although the nuclear division is reported to be longitudinal. 

 Consequently, if one speaks simply of stichobasidium, one understands 

 the Cantharellus type in contrast to the Corticium bombycinum type. 



While in the holobasidium, no formation of septa follows nuclear divi- 

 sions, in the phragmobasidium, septal formation follows directly the 

 first and the second stage of division of the primary basidial nucleus (only 

 two stages of division are completed) so that the mature basidium is 

 divided into four cells. As in the holobasidium, it is divided into two 

 types according to its form and the direction of the nuclear spindles. In 

 the first type, the basidium is slender and the nuclear spindles lie longi- 

 tudinally at unequal levels; consequently the septa are placed crosswise 

 (Fig. 360). This type is called the Auricularia type after the first example 

 studied in detail. It corresponds to the stichobasidium. In the second 

 type, the basidium is spherical or pyriform; the nuclear spindles lie at 

 equal heights and are transverse. It is called, again for historical 

 reasons, cruciate or Tremella type and corresponds to the chiastobasidium. 



Each division of the phragmobasidium forms a protuberance which is 

 differentiated into a sterigma and spore. The nucleus migrates into the 

 spore, which is abjointed from the mother cell and is ready for discharge. 

 In the Auricularia type, the sterigmata are inserted laterally; the Auricu- 

 laria basidium is, consequently, a pleurosporous phragmobasidium. In 



