MICHIGAN ACADEMY OF SCIENCE. 317 



of altitude which outdoors gives an opportunity for upward sweep of the 

 wind. Nevertheless the following experiments were performed. 



Field Experiments in Spore Dispersal: 



For this purpose a tube about 14.6 meters (48 ft.) long, 32.5 cm. 

 (14 in.) high, and 30.5 cm. (12 in.) wide was constructed thus: The 

 framework was made in three equal sections, using strips of yellow pine 

 2.5 cm. (1 in.) square. Each frame was then covered on the outside witli 

 wrapping paper and the seams thoroughly glued. The sections were set 

 up outdoors in a horizontal position one meter above the ground and the 

 ends joined together by covering with more paper. Since the wind at 

 the time was blowing from the east, the tube was set up in an east and 

 west direction. Petri dishes containing agar were then placed at 60 cm. 

 (2 ft.) intervals on three boards about 5 meters (16 ft.) long, 15 cm. 

 (6 in.) wide, and 1.25 cm. (3/2 in.) thick, and held in place by driving 

 two-i:)enny nails into the wood. The boards with the dishes of agar 

 were then shoved into the tube so that they rested on the bottom frame- 

 work. In this manner a means of catching spores at .6 m. intervals along 

 the entire 14.6 meters (48 ft.) was obtained. 



The dried spores used in this experiment were prepared in the follow- 

 ing manner: The growth from a clover juice culture was removed and 

 shaken with a little water in order to wash oft" many of the spores. The 

 spores were then precipitated from suspension by centrifuging. They 

 were then dried over CaCL, in vacuo, and kept in a tightly stoppered 

 tube until ready for use. Just before using, those which were massed 

 together in small dried lumps were ground lightly in a mortar. 



The dried spores were slowly released into the east end of the tube 

 through a small funnel inserted through a hole in the top side. This 

 was done gradually, by rubbing a little at a time between the fingers and 

 dropping into the apex of the funnel. Just inside of the west end of the 

 tube an anemometer was placed so that the center of the wind receiving 

 device was in line with the axis of the tube. The wind was permitted to 

 blow through the tube 33 minutes from the time the first spores were 

 released and then both ends of the tube were closed. Tlie anemometer 

 registered 34,476 meters during this time, which is equivalent to a 

 velocity of 6.268 kilometers (3.93 miles) per hour. The reading given 

 by the anemometer cannot be considered more than approximate, because 

 the wind was constantly changing direction slightly, and the wooden 

 framework inside the tube impeded, to a certain extent, the velocity of 

 the air whicli passed through the tube. 



The dishes were later examined microscopically and all except those 

 located at the 3.6 m. (12 ft.), 4.2 m. (14 ft.), 6.7 m. (22 ft.), and 8.5 m. 



