1906] FULTON—CHEMOTROPISM OF FUNGI 87 
rinsed in alcohol and afterwards soaked in two changes of sterile 
redistilled water. The media used were sterilized, whenever possible, 
under 15 Ibs. pressure of steam, or by fractional sterilization at 100° C. 
Except in those experiments in which capillary tubes were used, 
contaminations were of rare occurrence; whenever contamination 
was apparent, the experiment was disregarded in tabulating results. 
With few exceptions the chemicals used were the chemically pure 
_ preparations of reliable manufacturers. The water used in making 
up test solutions was redistilled in glass apparatus. All experiments 
were made in duplicate, and were repeated when occasion demanded. 
A fairly constant temperature of 28-29° C. was maintained for the 
cultures. Beet decoction, made by boiling 450%" fresh weight of 
sugar beet root in 1,000°° tap water, was the usual basis of nutrient 
agar and gelatin media. The stock decoction was diluted two to 
ten times for use. 
TESTS FOR CHEMOTROPISM. 
The capillary tube method.—In the first tests PFEFFER’S (26) 
method with capillary tubes was used. These tubes were filled 
with the chemical solutions under the air-pump, were rapidly rinsed 
in sterile distilled water, and were placed on the cover glasses in 
drops of the culture medium, while it was still liquid. The cover 
glasses were then inverted over Van Tieghem cells made up in the 
way described by CLarK (3), and were sealed to the cell rim with 
vaseline. A small quantity of liquid, the same in composition as 
that used in making up the culture medium, was placed in the bottom 
of each cell. Observations were made when the hyphae were 40-75 
spore-diameters in length, and again three or four hours later when 
growth had become indefinitely great. In estimating the effects 
of the chemicals, regard was had for the hyphae from spores lying 
within a radius of one lumen diameter from the opening of the tube, 
and such other hyphae from more distant spores as entered this 
area. Only those were held to be chemotropically affected that 
showed a turning out of their former courses toward or away from 
the tube opening. In recording the observations Mryosxt’s method 
was used; to denote a turning away of 12 per cent. to 37 per cent., 
the symbol r was used; for a turning away of less than 12 per cent. and 
an attraction of less than 12 per cent., the symbol 0; for an attraction 
