96 BOTANICAL GAZETTE [FEBRUARY 
In similar series with celloidin films, the turning from one gelatin 
layer to another was about equal to that obtained with mica plates. 
When the spores were spread on the film without a culture medium, 
very few of the hyphae grew through the holes, the percentage of 
turning being negligible. The hyphae in these cases were sur- 
rounded by a distinct film of condensed moisture. 
TESTS FOR OTHER FACTORS. 
The tests thus far have failed to give evidence of the existence 
of any marked chemotropism. There has been at the same time a 
considerable and fairly constant turning of the hyphae from a medium 
containing spores to a sterile medium, when these were separated 
the one from the other by any one of several partitions. Since this 
turning is apparently unaffected by the chemical relationships of 
the media employed, the cause of the turning must be sought in 
other factors. Two possibilities at first present themselves; the 
mechanical partitions may have a thigmotropic or other influence, 
or the germinating spores themselves may affect the direction of 
owth. 
Tests without mechanical partitions —A slight modification of 
the method employed by CiarK (4) was used. A large drop of 
agar, 8™™ in diameter, was placed in the center of a sufficiently 
large square of glass; this drop was surrounded by four drops of 
about 5™™ diameter, equidistant from the first, and with a space 
of about 3™™ between each smaller drop and the larger one. Non- 
nutrient agar and to per cent. sugar-beet agar were used for the 
drops, and were arranged in four combinations: the central drop 
was of nutrient agar and two small drops diagonally opposite each 
other were of nutrient agar, the other two being non-nutrient; the 
central drop was of nutrient agar, two small drops adjacent to each 
other of nutrient agar, and the other two of non-nutrient agar; two 
similarly arranged combinations had central drops of non-nutrient 
agar. The fungi used were Monilia sitophila, Mucor stolonijer, 
and Botrytis vulgaris. A few spores were sown with the platinum 
‘needle at the center of the large drop in each preparation; the cover 
was inverted over a Stender dish containing distilled water and was 
sealed to its rim. The growth was watched until the hyphae had 
grown about two-thirds of the distance from the center to the margin 
