252 BULLETIN 94. 



africana. A. proliferus"' (deBary) saprophytic on dead seedlings 

 and insects in water ; A. vexans 2 * (deBary) in dead seedlings and 

 in diseased potatoes ; A. anguillulae-aceti* (Sadebeck), parasitic 

 in Anguillula aceti ; A. sadebeckionus (Wittmack) producing 

 epidemics of diseases in lupines and peas. Several other species 

 have been impectly described. 



A POTTING BED FUNGUS NEW TO AMERICA. 

 Completoria Complens Lohde. 



This is an organism which is parasitic upon fern prothallia 

 grown in forcing houses. It has been known in Europe for sev- 

 eral years but was first found in this country during the winter of 

 1893-4, i n the botanical conservatories of Cornell University, 

 while studying the rotting of prothallia induced by Artotrogus in 

 termedius (deBary), described in a former paragraph of this paper. 

 Ultimately the prothallia decay but the first signs of disease when 

 caused by this parasite alone is the appearance of a yellowish or 

 yellowish brown color imparted by the prothallia as they lie on 

 the soil of the pot or bed. The prothallia are so small that 

 usually the color appears to reside in the entire prothallium when 

 seen by the unaided eye. When examined by the aid of a 

 microscope, however, unless the prothallium is in the last stages 

 of the disease, the decay will be seen to be confined to " spots." 



These spots vary in color from a yellowish green to yellowish 

 brown, deep brown and finally blackish, dependent on the phase 

 of the injury to the cell and its contents. At first the injury is 

 confined to single cells either near together or far isolated, on the 

 margin of the prothallium or at any point over its surface. 



When the trouble is well advanced and there are numerous cen- 

 ters of the disease, as frequently happens, the prothallium will 

 present a checkered or mosaic appearance, the different pieces of 

 the mosaic being colored with the various shades of color detailed 

 above. It also presents at this time quite a ragged appearance 

 because many of the cells are dead and the disintegration of their 

 contents makes holes in the plant and rifts in its edges. A short 



2 *Pringsh. Jahrb. f. wiss. Bot. II., 182, 1860. 



2 sjour. Bot. V.,ii9, 1876. 



26 Bot. Centralbla. XXXIX., 318, 1887. 



