and Laboratory Methods. 2387 



lution. Should the long axis of the seedling make less than a right angle with 

 the axis of revolution, gravitation is iiotivholly neutralized. Observe the direction 

 of growth in both stems and roots at the end of 8 to 12 hours. If properly set 

 up they will continue to grow in a straight line. 



7. The Directive Action of Gravitation when Light is Excluded or Neutralized. — 

 The first condition is fulfilled by placing a plant horizontally in a dark chamber, 

 and is practically the same as the first experiment under the study of Geotropism. 



To fulfill the second condition, change the damp chamber of the klinostat 

 from the vertical position shown in Fig. 17 to a horizontal position, and fasten 

 several mustard {Sinapis a/da) seedlings to the wooden bar in such a manner 

 that they will be in a horizontal position when the bar is inserted in the damp 

 chamber. Cover the damp chamber of the klinostat with a dark box which has 

 a small window admitting light on a level with the horizontally revolving seed- 

 lings. In both cases it will be found that pronounced geotropic curves appear. 



8. The Directive Action of Light when Gravitation is Neutralized.— Cover the 

 damp chamber of the klinostat with a light proof jacket, leaving an opening of 1 

 square cm. on one side of the chamber. The covering may easily be made of 

 black paper and held in place with rubber bands. Adjust the damp chamber in 

 a vertical plane as in Fig. 17, so that gravitation will act equally on all sides and 

 light comes constantly to the plants from one side. Mustard or radish {Raphanus 

 sativns) seedlings should be used in this experiment. If adjusted properly, they 

 will exhibit heliotropic curves at the end of 8 to 10 hours of revolution. 



9. Direction of Growth when the Stimuli of both Light and Gravitation are 

 Neutralized. — Employing the same apparatus used in the last experiment, remove 

 the dark covering from the damp chamber of the klinostat and cover the klinostat 

 with a dark box containing a small window, in front of which the seedlings pass 

 as the chamber revolves. As before, use mustard or radish seedlings. The 

 result will perhaps be a little more striking if the seedlings are first laid in a hori- 

 zontal position long enough to acquire decided curves. The curves will be 

 greatly diminished or straightened out entirely after 12 to 20 hours of revolution. 

 University of Michigan. HowARD S. ReeD. 



Laboratory Outlines for the Elementary Study of Plant 



Structures and Functions from the Standpoint 



of Evolution. 



THE HIGHER FUNGI AND LICHENS— Continued. 



XXXIX. Bovista phtmbea Pers. Class, Basidiomycetes. Order, Lycoper- 

 dales. Family, Lycoperdaceae. 



This puffball of a dark-brown color, when mature, is usually abundant in 

 pastures, where it may be gathered in any season. It has a more or less spher- 

 ical body, usually from one-half to one inch in diameter. 



1. Sketch one of the fruiting bodies, showing the inner peridium with an 

 aperture at the apex for the discharge of the spores. 



