io S etc hell. — An Examination of the Species 
Physoderma macular e, Karst., Fung. Fenniae Exs., No. i. 1 86 1 ! 
(not Wallroth.) 
Aecidium incarceraium , Berk., in Rab., Fung. Eur., No. 1492. 1871 ! 
Protomyces macularis, Thuem., Myc. Univ., No. 1417. 1879 ! 
Phyllosticta alismatis, Pass., Erb. Critt. Ital., Ser. II, No. 1093. 1881 ! 
Doassansia alismatis , Holway, in Ellis, N. A. Fungi, No. 1485. 1885 ! 
— — Johanson, in Eriks., Fung. Par, Scand., No. 263. 1888! 
johanson, in Pazschke, Fung. Eur., No. 3601. 1890! 
Doassansia sagittariae, ( Westend .), Fisch. 
D. sagittariae is found in Europe and in both Americas, 
inhabiting the leaves of species of Sagittaria. In Europe the 
host-plant is the common S. sagittifolia , in North America 
it is found upon the varieties of the wide-spread N. variabilis 
and also upon S. heterophylla according to Fisch ( 1 . c., p. 407) ; 
but this last may be a mistake, for Fisch quotes Demetrio’s 
specimens from Missouri (Fung. Fur., No. 2902 a), which are 
upon N. variabilis , but does not mention S. variabilis among 
the hosts for this species. There is no reason why D. sagit- 
tariae should not occur upon S. heterophylla. Mr. G. P. 
Clinton has collected it at Dixon, 111 ., on S. gr amine a. In 
South America it is found upon S. montevidensis. 
Upon the leaves of all these species the Doassansia forms 
circular spots of a light yellow colour, which soon becomes 
inclined to brownish and punctate with the rather dark sori. 
There seems to be no swelling of the leaf, and the general 
appearance is very much like that of D. alismatis. The spots 
grow to be of considerable size by the continued formation of 
new sori at the periphery. 
The sori are situated either in the single layer of palisade- 
parenchyma in the spaces just under the stomata, or in the 
spongy parenchyma in the spaces just over the stomata, or in 
the same tissue midway between the two surfaces in the 
ordinary intercellular spaces. There are about equal 
numbers of sori under each leaf-surface, so that the fungus 
can scarcely be said to inhabit the upper surface of the leaf 
(see Fisch, 1 . c., pp. 407 and 415). 
