580 COMPARATIVE MORPHOLOGY OF FUNGI 



consists of a fascicle of hyaline hyphae whose ends are rich in plasma 

 and clavately swollen. Every cell divides by a septum into an apical and 

 a basal cell which latter undergoes no further division, but elongates 

 and becomes the stipe cell. The apical cell, under certain conditions, is 

 divided by a longitudinal wall into daughter cells whose number is 

 characteristic for each species. This apical cell divides into an upper 

 spore cell and a lower cyst cell. The spores adhere laterally in a firm 

 dome. In this type, there arise as the spore bodies a definite number of 

 spores and cysts, constant for each species, which are also borne by a 

 definite number of hyphae. In other groups, the relationships are more 

 complicated in that the peripheral spore cells differentiate as cysts; in 

 the central ones septation is absent whereas, in still others, the spores 

 themselves become septate and two celled. The cysts in this genus are 

 filled with a viscid substance and burst at maturity. Their function is 

 not yet clear; possibly they serve for water storage or they facilitate the 

 separation of spores from the sporiferous hyphae or attach the spores to 

 a new substrate. 



In contrast to all these forms, which have probably evolved from 

 Uromyces in an ascending series, there are three other genera which 

 are best considered as a degradation series. In Zaghouania (Fig. 391, 1) 

 and Cystopsora, the basidia do not reach the open air through a germ 

 pore from the teliospore but are completely formed within it, rupture 

 the teliospore wall near the stipe and only protrude their tip from the 

 slit; perhaps we have here an adaptation to a dry climate. Ochropsora 

 no longer forms teliospores and the basidia arise directly from binucleate 

 mycelium, as in Coleosporium. Since transitional forms are still unknown, 

 the significance of these three genera is naturally ambiguous. 



The germination of teliospores, as that of the probasidia of the 

 Auric ulariaceae, produces a new spore form with basidia and basidiospores. 

 The single cells form a short germ tube through the germ pore, into which 

 the diploid nucleus migrates. That its first division is meiotic has been 

 definitely proved for Cronartium ribicola among others, since in the first 

 stage of division sixteen chromosomes have been counted, while the 

 haploid chromosome number is eight (Colley, 1918). The basidia are 

 regularly pleurosporous phragmobasidia, as those of the Auriculariaceae, 

 but there are exceptions, such as Coleosporium Pulsatillae where the septa 

 are vertical as in the Tremellaceae (Weir, 1912). All the sterigmata are 

 equally short in the simpler forms, as in the Coleosporiaceae (or in Auri- 

 cularia and Iola javensis of the Auriculariaceae). When mature they 

 excrete at their tip a small drop (9 to 10ju) which pushes the basidiospore 

 to one side. When the basidiospore and drop are suddenly hurled away, 

 with the aid of air currents, they are thrown nearly a millimeter; an 

 initial velocity of about 9 cm. per second is reached (Dietel, 1912; Buller, 

 1924). 



