EXOBASIDIUM. 



425 



from each a spindle-shaped spore is abjointed (Fig. 257). The 

 basidiospores divide in water by formation of cross-septa, and 

 a germ-tube arises from each terminal cell. On a young leaf 

 of Vaccinmm the germ-tube 

 penetrates and gives rise to 

 a mycelium (Fig. 258); on 

 other substrata the germ-tube 

 sprouts into several very fine 

 sterigmata, from the extremi- 

 ties of which a series of conidia 

 are abjointed; the conidia 

 may give off secondary coni- 

 dia, perhaps also tertiary. In 

 nutritive solution, Brefeld ob- 

 tained an increased number of 

 germ-tubes and a continuous 

 production of conidia ; in air, 

 conidia were produced on conidia, but inside the solution the 

 conidia gave off hyphae from which new conidia arose. 



Fig. 257. — Bxobasidium vaccinii. The basidial 

 layer is shown developing from the intercelUilar 

 myceliiim of the shoots. (After Woronin.) 



Fig. 258. — Exobasidium vaccinii, Germinating basidiospores. The septate spores 

 have given off germ-tubes which penetrate into the cowberry leaves, either by 

 stomata or through the epidermis. The lowest spore is forming conidia. (After 

 Woronin.) 



This Eosobasidium is very common on the cowberry ( Vaccinium 

 Vitis-Idaea)} It occurs less frequently on the bilberry (Vac- 



^ Several American Ericaceae are given as host-plants in the "Host-Index." 



