198 



SPORE DISSEMINATION 



filiform cells, which have generally been regarded as basidiospores, 

 is formed. Buller, however, regards them as steri^mata of a 

 highly specialized type for two reasons: (1) they are never shot 

 away and therefore do not serve to disseminate the fungus, and 



Fie. 36. Spore discharge by Tilletia tritici. A. Germination of chlamvdo- 

 spore, formation of special sterigmata that have fused in H-shaped fashion, 

 and stages in formation of true basidiospores or sporidia. B. Tip of sterigma 

 with mature basidiospore and a droplet of fluid that serves in forcible dis- 

 charge. C. Basidiospore that has just been discharged with droplet clinging 

 to base of basidiospore. (After Buller.) 



(2) while still attached to the basidium, they oive rise to sickle- 

 shaped spores, asymmetrically placed, that are forcibly expelled. 

 These spores may cause infection, and Buller consequently regards 

 them as the true basidiospores of the Tilletiaceae. 



As has often been observed, the specialized sterigmata may form 

 H-shaped conjugations. Either from these pairs or from a single 

 unpaired member, a septate hypha may arise, from which the 

 sickle-shaped basidiospores are abstricted. In T. tritici these 



