XIV LIST OF ILLUSTRATIONS 



FIG. PACiK 



29 Seeds on wet sand with different amounts of air at tlieir disposal 33 



30 Apparatus for determining whether germinating seeds produce carbon 



dioxide 34 



31 Method of measuring the amount of carbon dioxide produced by ger- 



minating seeds 34 



32 Method bf measuring the temperature of germinating seeds 36 



33 Method of determining whether air exists in the soil 37 



34 Apparatus for determining how deep seeds should be planted 39 



35 A planting stick 40 



36 Screens for seed-beds 41 



37 Method for testing the permeability of the seed-cover to heat 42 



38 Arrangement for testing the swelling power of a single seed 49 



39 Arrangement for testing the swelling power of a mass of see<ls 51 



40 Apparatus for demonstrating that swelling seeds exert pressure 53 



41 Bottle broken by swelling seeds 54 



42 Germination of Squash 54 



43 Later stage of germination of Squash 54 



44 Squash seeds arranged for germination experiment 55 



45 Germinating Cocoanut cut lengthwise 57 



46 Buckeye cut open 58 



47 Buckeye. Plumule emerging from between elongated stalks of seed- 



leaves 59 



48 Buckeye. A later stage 59 



4!) Buckeye. A still later stage 60 



50 Scarlet Runner Bean germinating 60 



51 Apparatus for demonstrating that osmosis exerts pressure 61 



52 Api)aratus for measuring pressure due to osmosis 62 



5;{ Section of a bit of the seed-leaf of the Horse-bean 65 



54 Water-bath 67 



55 Filaree seeds burrowing into cotton 70 



56 Corn making its way above ground 71 



57 Bean getting above ground 71 



58 Castor-bean twisting itself into a loop 72 



59 Apparatus for measuring the force of the upward growth of the plant. . 73 



60 Modification of apparatus shown in Fig. 59 74 



61 Arrangement for weighting an upward -growing stem 75 



62 Modification of arrangement shown in Fig. 61 75 



63 Bean with stem marked to determine region of greatest growth 77 



64 Contrivance for marking stems in manner shown in Fig. 63 78 



65 Scarlet Runner Bean with top {terminal bud) removed 79 



06 . Radish seedlings growing upward along the glass side of a bo.\ 7(1 



07 Sunflower seedlings penetrating the soil SO 



08 Squash seedlings endeavoring to penetrate the soil 81 



