3 2 The Colorado Experiment Station 
ACKNOWLEDGMENT. 
The writer wishes to thank Prof. B. O. Longyear and Miss 
M. A. Palmer for the preparation of the colored plate. 
EXPLANATION OF PLATES. 
PLATE I.—Fig. 1, Ps. medicaginis, n. sp.; 24 hour agar culture 
stained with aqueous fuchsin; original x 1,000, reduced by engraver 6:5. 
Fig. 2, Ps. medicaginis, n. sp.; 48 hour agar culture stained with 
aqueous fuchsin to show the formation of filaments; original x 1 000 
reduced by engarver 6:5. 
Fig. 3, Ps. medicaginis, n. sp.; surface agar colony 7 days old, photo¬ 
graphed by transmitted light to show concentric rings of growth- original 
x 20, reduced by engraver 6:5. 
Fig. 4, Ps. medicaginis, n. sp.; surface agar colony 7 days old, photo¬ 
graphed by reflected light; original x 20, reduced by engraver 6:5. 
PLATE II.—Fig. 1, Ps. medicaginis, n. sp.; agar colonies 7 days old 
showing deep and surface colonies by transmitted light; original x 20 
reduced by engraver 3:2. 
Fig. 2, Ps. medicaginis, n. sp.; agar colonies 7 days old showing 
deep and surface colonies by reflected light; original x 20, reduced by 
engraver 3:2. 
Fig. 3, Petri dish showing pure culture of Ps. medicaginis colonies 
2/3 natural size; original x 1, reduced by engraver 3:2. 
PLATE III. Fig. 1, Alfalfa stem, inoculated by smearing the 
freshly scraped stem with a 48 hour agar culture of Ps. medicaginis x 2* 
4 0 days after inoculation. 
Pig- T Diseased alfalfa stem showing the yellowish olive green 
color, characteristic in the early stages, x 2. Field specimen, natural 
inoculation. 
Fig. 3, Diseased alfalfa stem showing the blackened condition in the 
late stages of the blight, x 2. Field specimen, natural inoculation. 
Fig. 4, Alfalfa stem, inoculated with a 48 hour agar culture of Ps 
medicaginis by means of needle pricks, x 2; 15 days after inoculation. 
Fig. 5, Alfalfa leaf showing diseased, yellow areas, apparently of 
water pore or stomatal infection, x 2. Field specimen, natural inocula¬ 
tion. 
NOTE. Figs. 1 and 2, Plate I, were made by the writer with a 
Leitz Photomicrographic apparatus in connection with the Leitz micro¬ 
scope, 1/12 oil immersion objective, eyepiece I; Welsbach gas light- 
Cramer’s Medium Isochromatic Plates. Figs. 3 and 4, Plate I, and Figs 
1 and 2, Plate II, were made by the writer with the Leitz Photomicro- 
graphic apparatus in connection with a Leitz Microsummar 35 mm f-4 
5. Plate III. was prepared by Miss M. A. Palmer and Prof. B O Long! 
year from fresh material. * ’ & 
