LIST OF ILLUSTRATIONS XV 



wo. PAGE 



69 Apparatus for deterniiiiing how much force the root exerts in growing 



downward 82 



70 Apparatus for determining force of growth of a root 84 



71 Root marked in order to determine the region of greatest growth 85 



72 Plant attached to support ready to have root cut off 87 



73 Seeds pinned to corks which are floating on water 88 



74 Seeds arranged with caulicles resting on mercury 89 



75 Arrangement for causing germinating seeds to revolve slowly 91 



76 Water-wheel for making germinating seeds revolve rapidly 93 



77 Arrangement for testing effect of moisture on direction of growth of 



roots 95 



78 Arrangement to test behavior of roots in moist air 90 



79 Arrangement for ascertaining whether roots grow in the direction of 



moisture 96 



80 Apparatus for observing behavior of roots as they encounter obstacles. 97 



81 Apparatus designed to test behavior of side roots under the influence 



of gravity 98 



82 Modification of apparatus shown in Fig. 80 99 



83 Radish seedlings showing root-hairs 100 



84 Root-hairs of Radish 101 



85 Cutting of Wandering Jew in water, showing root-hairs 102 



86 Apparatus for measuring rate of evaporation from a saturated soil 114 



87 Method of supplying water to apparatus shown in Fig. 86 114 



88 Four lamp-chimneys filled with soil for the purpose of studying tlie 



evaporation 115 



88rt New growth on cultivated and uncultivated Apricot trees 11(1 



89 Diagram of fairly dry soil showing relations of root-hair to surround- 



ing particles lli> 



90 Cross-section of a root as it grows in the soil 120 



91 Artificial root-hair 123 



92 Diagram to illustrate effect of ideal plowing ]2(i 



93 Part of furrow slice (of Fig. 92) magnified to show floccules or soil- 



crumbs ; 127 



94 A single soil-crumb magnified 128 



95 A still for making distilled water ];!7 



96 The result of a water culture of Wandering Jew 140 



97 Apparatus to determine whether the root excretes acid 143 



98 Tubercles on roots of Clover 149 



99 Two Scarlet Runner Beans of the same age, from one of which the 



seed-leaves were removed shortly after germination 163 



100 Germinating Date 180 



101 Leaf of English Ivy deprived of starch and placed in water 182 



102 Arrangement for excluding light from a part of the leaf 182 



