DOASSANSIA. 323 



through tlie wall, remains tliin, but <u emeritin^ into an int'-r- 

 cellular space it soon thickens and branches into a mycelium. 

 Infection results in the appearanee of yellow spots, due to 

 rapid destruction of the chlorojihyll and death of cell-contents. 

 Kxperiuients in itermination have been carried out by Setchell 

 and I'.refeld. 1 



Doassansia sagittariae (\Ve-t. ) (Britain and U.S. America). 

 In leaves of Sn,iitt,i,-in. The spores, according to Urefehl, 

 in water, after hibernation. They produce unicellular 

 eelja with a terminal tuft of more or less -pindle-.-haped 

 conidia, which at once beuin to sprout and fall off. ( )u the 

 surface of a nutritive .solution they continue to sprout yeast- 

 like, and form close mouldy coatings. (Doassansia is the only 

 genus of tin- Tilletiae in \vhich Brefeld found yeast-like .-prout- 

 ini: of eonidia.) 



D. alismatis (Nees) d'.ritain and I'.s. America). Tliis 

 inhabits leaves ( ,f ^i//.s//,// /'/ ///"// and ./. natans, producing 

 knotty swellii The spores are enclosed in a layer of com- 



panion-. -dl- containin- air, whereby the masses swim on \vatei-. 

 (hi the promycelium the eonidia aiise from tufts of conidio- 

 s; the\- fuse in paii-s. and -ecoiidary eonidia are de\ eloped 

 t-ai-li pair or even from -iu-le ennidia. 



D. Niesslii ide Toidi forms -mall spots on leaves of /,'nfn- 

 m/us a mix Until*. The >pores are surrounded by companion-cells 

 containing air. They -erminate before l-'a\inu the sp,,re-pat<-h, 

 and pi'odii. -.- eonidia, even -i-condai'y eonidia. before rupture of 



the hoM-epidermis take- place. P.refeld dex-ril'es the S] . 



as ^ei-iiiinatinu' in water to form a \eiv -boil promyeeliuin 

 with -holt thick eonidia which fuse in pairs and Ljive oil' lai 



:M!.IIV eonidia from their apices. In nutriti\e solulioii 

 eonidia are developed, which give o|f -eptate filament- uhenee 

 furthe]- eonidia aii-e. Aerial conidia are ultimately developed. 



Magnus found that the spores, of l>. alismatis, />. Niesslii, 



and other species jerminateil at mice on reaching matmily. 



I'.lefeld, ho\\e\e]', folllld that ill!- took place o]|ly aflcf they 



had lain ovei' wintej-. It may In- that heie, as with some 

 higher plant- I-.'/. Pinia ' '< nii'i'ii). there is an immediate 

 ea|. ability of -ei niiiial ion, but also a d. -felled, the lalt.T re(|iiiriii'j 



IH II, .1 I ,/, \i., |s;i-J. I'.i.i.M. >' In IIIIIK hiil', II. i' MI., 



1895 



