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IOWA ACADEMY OF SCIENCES. 
throughout. At first there was a slight green tinge, but 
this soon disappeared. 
Asparagin, 1.0 g., glycerin, l.Og., M. nahrlosung 1.00 g., 
white membranous growth, tinged with purple at the top. 
Medium with a decided greenish tinge. 
Asparagin, 1.0 g., glycerin, l.Og., cane sugar, 0.5 g., M. 
nahrlosung, 100 g. A light purple scum, white mem- 
branous grow^th at the base of tube, medium with a green 
tinge. 
As above noted the presence of asparagin is favorable to 
growth When this organism is grown in a medium con- 
taining asparagin, the green tinge is almost invariably 
present. The color is very similar to that which appears 
when an alcoholic solution of the violet coloring matter is 
treated with a solution of sodium hydrate. 
Peptone, 1.0 g., cane sugar, 1.0 g., water, 100 g. Light 
purple scum, considerable light sediment. 
Peptone, l.Og., beef extract, 1.0 g., cane sugar, l.Og., 
water, 100 g. A very heavy, dark, almost black, purple scum, 
thick and decidedly wrinkled, was formed. The maxi- 
mum amount of growth and color obtained, was had in 
this medium. 
Peptone, 1.0 g. beef extract, 1.0 g., dextrose, 1.0 g., water, 
100 g. The growth similar to the preceding. 
Peptone, 1.0 g., dextrose, l.Og., water, 100 g. Color pro- 
duction somewhat less than in the preceding. Beef 
extract seems to be very favorable to color production. 
Peptone, 1.0 g., ammonium sulphate, 1.0 g., potassium 
nitrate, 1.0 g., M. nahrlosung, 500 g. Purple scum similar to 
the preceding is formed. 
Arrowroot Starch was also used as a medium. This is an 
almost pure starch containing very little proteid. Growth 
was slight on slant, but well colored. 
Potato . — On the potato the growth was not so luxuriant 
as that which has been described by various authors. It is 
generally stated that the growth is luxuriant and spread- 
ing. In this study it formed a brownish, or yellowish 
white, glistening, raised growth, which in the course of 
