103 
leaves carefully. Dr. Farlow* refers to Boestelia aurantiaca as possibly 
being perennial. 
Mar sonia juglandis (Lib.) has been quite destructive to Jug Ians cin- 
erea and J. nigra, causing brown spots to appear on the leaves. Trees 
thus affected lose their foliagepre maturely. Mar sonia Marti nil Sacc. 
and Ell., commonly occurred on Quercus alba and Q. rubra , causing pale 
colored spots with two-celled spores. Phyllactinia suffulta occurred de¬ 
structively on Fraxinus at Ames the past summer. 
REMARKS ON THE FUNGUS OF A POTATO SCAB. 
(Sponyospora solani Brunch.) 
By Prof. Cf. de Lagerheim. 
In purchasing some potatoes at a market in Quito for use in bacterial 
cultures, I noticed Avhile cleaning them that they were affected with 
black warts. An incision into these warts convinced me that they were 
caused by the fungus Spongospora solani , described by Brunchorstt 
several years ago. This disease is said not to occur in North America,! as 
the disease known as u scab ” is there produced by other fungi. Since 
South America is the home of the potato, it seemed to me of interest to 
study this disease here. The disease is generally known in Quito, and 
manifests itself on potatoes from various localities. It is called u Oara,”§ 
and is supposed to be occasioned by the gnawing of worms. 
The microscopic appearance and the behavior of the warts coincide 
fully with the description and illustration given by Bruucliorst (loc. cit., 
p. 219, Plate i, Fig. 2). While the microscopic illustrations of Brunchorst 
were quite accurately drawn, they were, nevertheless, altogether erro¬ 
neously interpreted. The wart-forming tissue, which he considers as a 
part of the potato altered by the disease, is the pseudo-parenchyma of 
fungus hyphse, in which the characteristic spore balls arise. The fun¬ 
gus is, therefore, not a Myxomycete, and has no relation to Plasmodio- 
phora. In cross sections of the warts hyplue are often seen growing 
out of the pseudo-parenchyma, their membranes being precisely of the 
same color as the cells of the pseudo-parenchyma. The membranes of 
the liyplire are of a more or less purple-brown color. In a wart that 
does not yet contain spores the hyphae are filled with a colorless proto¬ 
plasmic substance, which is very often full of vacuoles. It is perhaps 
*Farlow: Tlie Gymnosporangia or Cedar Apples of the United States. Memoirs 
Boston Soc. Nat. Hist. 
t Regarding a very widespread disease of the tubers (Bergens Museum, Aars- 
bcretning, 1886) Bergen, 1887. 
t According to Tliaxter. Report of the Mycologist, p. 6 (Fourteenth Annual Report 
of the Connecticut Agricultural Experiment Station, 1890), New Haven, Connecticut. 
§ A word from the Quichua language, which means scab in English, or sarna in 
Spanish. 
