THE INFLUENCE OF GRAVITY ON THE DIRECTION 
OF GROWTH OF AMANITA 
STELLA G. STREETER 
(WITH THIRTEEN FIGURES) 
The following account is a record of a series of experiments carried 
on at the Biological Laboratory of the Brooklyn Institute at Cold 
Spring Harbor, under the direction of Professor D. S. JOHNSON, 
during the summers of 1906 and 1908. The object was to determine, 
if possible, the reactions of some of the common toadstools to the 
gravity stimulus. The main points under consideration are the 
promptness and accuracy of the response, the duration of the response 
after an efficient stimulus, the location of the zone of elongation, and 
its relation to the responsive zone. The conclusions here stated 
were drawn from observations made on about 3000 specimens, 
collected in the woods and replanted where conditions could be con- 
trolled. With the greatest care not more than one out of every ten 
planted yielded a satisfactory record. The agarics break easily, 
often from their own weight, when placed in a horizontal position; 
some shriveled instead of developing, and many were infested with the 
larvae of various insects, which fact was not apparent until the toad- 
stool was near maturity. 
The species used in these experiments were Amanita phalloides 
Fr. and A. crenulata Peck. These forms were chosen because they 
have long stipes, because transplanting seemed in no way to retard 
the normal development, and because they were very abundant. 
The food supply is stored in the button, so that the plant is not 
seriously affected by removal from the mycelium. The plants were 
collected from the woods just after they broke through the ground, at 
the stage when the pileus is beginning to break through the volva. 
Each was taken up carefully with some of its surrounding soil, 
carried to the laboratory, and there planted again in a tumbler. 
When it had been allowed to rest in the normal vertical position in a 
dark chamber for a short time, a careful drawing of each specimen 
was made in the following manner. The plant was placed, with the 
Botanical Gazette, vol. 48] . [414 
