ii8 RESEARCHES ON FUNGI 



end of the experiment the upper part of the fruit-body, i.e. the 

 sporangium, the subsporangial swelling, and the top of the stipe, 

 was observed by looking downwards upon it through the peep-hole 

 of the cover-glass, as indicated by the arrow shown in Fig. 56, B. 



The experiment began on May 3 at 9 o'clock in the morning. 

 For the first ten minutes, the fruit-body remained in its original 

 position, as shown in Fig. 56 at A ; but, three minutes later, its 

 stipe was observed to have turned very slightly toward the light, 

 so that the presentation time was estimated to have been about 

 ten minutes. Half an hour later, i.e. forty minutes after the begin- 

 ning of the experiment, the stipe had bent toward the light through 

 an angle of 45° ; and at the end of eighteen further minutes, i.e. 

 approximately one hour after the beginning of the experiment, 

 the stipe had bent through a complete right angle and had turned 

 the subsporangial swelling and sporangium through 90° so that they 

 now faced the sunlight head on. Immediately after the heliotropic 

 movement had been completed, the top of the fruit-body was drawn 

 with the camera lucida. A study of this drawing, which is reproduced 

 in Fig. 57, shows that the motor region of the stipe, to which the 

 turning movement of the sporangiophore was due, was situated 

 almost at the top of the stipe, i.e. immediately under the topmost 

 region of the stipe which is distinguished by the presence of the 

 incomplete protoplasmic septum. 



A few minutes after the drawing shown in Fig. 57 had been made, 

 the sporangiophore shot away its sporangium, and the sporangium 

 struck and stuck to the narrow window-slit shown in Fig. 56 at 

 A and C. 



At the beginning of the experiment, a beam of sunlight which 

 fell on the subsporangial swelling formed a spot of colourless light 

 on the colourless protoplasm lining the inner side of the back wall 

 of the swelling. This spot of light could be observed with the 

 microscope. As the subsporangial swelling was gradually being 

 turned through a right angle by the growth-movement of the stipe, 

 the spot of light was seen travelling slowly down the side of the 

 swelling until at last it settled on the perforate protoplasmic 

 septum at the top of the stipe. For the first twenty minutes or 

 so of the turning movement of the stipe, the spot of light travelled 



