220 PLANT PHYSIOLOGY 



from which the cotyledons are not raised (Horse Bean, Corn), in 

 positions as different as possible. Give favorable conditions for 

 growth, and observe the positions taken. 



As soon as the roots are 2-3 cm. long, swing the plants in their 

 respective planes through 45 from the vertical, and later, after they 

 have grown somewhat longer, swing them to 90, and observe results. 



MOIST-CHAMBERS. These are of very diverse forms according to their 

 particular uses, but all in common should provide a constant water-supply 

 with a saturated atmosphere, darkness with ready accessibility to observa- 

 tion, and good aeration. A simple form is a germination box (originally 

 described by SACHS), viz., a sphagnum- or sawdust-filled box having a slop- 

 ing glass side; if the seeds are planted against the glass, well above the 

 middle, the developing roots will show clearly against the glass. The box 

 may well be made of wire netting of shallow form, with the glass as a remov- 

 able cover, the whole being stood against a support with the glass sloping. 

 Or a large funnel in upright position is a good substitute. Another very 

 excellent form, especially useful for demonstration purposes, is made from 

 two sheets of glass holding between them a sheet of soft dark -colored felt 

 paper (herbarium dryers) saturated with water (described by PEPOON in 

 School Science, 2, 1902, 179). Other forms of the same type (often called 

 Root Cages) are described by BARNES in his "Plant Life" (Holt & Co., 1898), 

 200, and by LLOYD in the Plant World, 8, 1905, 262. The seeds are placed 

 in any desired positions between paper and glass, and, with added bits of paper 

 at the corners to prevent too great compression of the seeds, the glasses and 

 paper are clamped together by wooden clothes-pins. A common form of 

 moist -chamber is a glass box or jar lined in whole or in part by filter paper kept 

 saturated, and even a glass-stoppered bottle, with water in the boltom, is suf- 

 ficient for many purposes. A good form is described by REED in Jour- 

 nal of Applied Microscopy, 4, 1901, p. 1499, and 5, 1902, p. 1890. SACHS 

 has also described a very complete moist-chamber for geotropic studies 

 (Flora, 80, 1895, 293). In most respects an ideal moist-chamber is formed 

 by a clean porous flower-pot in a saucer of water, either inverted with the 

 hole stoppered, or in ordinary position, with a saucer of water also as cover; 

 the whole arrangement thus has evaporating walls, and incidentally is mark- 

 edly cooled in hot times by the external evaporation. It may be made even 

 better by building a circular dam of modelling-wax on the inverted bottom, 

 thus forming a saucer in which water may be kept standing, to the more ready 

 saturation of the pot, especially if this be large. Aeration, for most purposes, 

 is amply provided by a daily blowing out, but it would be very easy to arrange 

 an aspirator to draw in saturated air. The one drawback to this chamber 

 is that its contents are not directly accessible to observation, a difficulty 

 which may be partially compensated by the use of openings drilled in the 

 sides and kept stoppered when not needed for observation, or covered by 

 glass windows cemented into the sides. But where frequent observation of 

 the entire object is desirable, as in the present experiment, a better chamber 

 is that shown by the accompanying figure (Fig. 59), made from a battery- 



