_Black Digger-wasp_ 73 _Black Digger-wasp and His Victim, Showing the Egg of the Wasp Attached_ 75 _Protecting the Burrow while Searching for Prey_ 79 _The "Cow-spit" Mystery Disclosed_ 81 _The Tiger's Head, from the Victim's Stand-point_ 84 _Initial. Branch of the Bittersweet_ 87 _A Bittersweet Covey_ 90 _Flushing the Game_ 92 _Specimen Twig_ 94 _Building Froth-tent_ 100 _Butterflies and Flowers_ 105 _A Row of Stamens_ 106 _The Parts of a Flower_ 109 _Historical Series, Showing the Progress of Discovery of Flower Fertilization_ 110 _The Garden Sage_ 120 _Cross-fertilization of the Sage_ 121 _Elastic Stamens. Anthers Inserted in their Pockets_ 124 _Elastic Stamens of Mountain-laurel_ 125 _Andromeda Ligustrina_ 127 _Fertilisation of Andromeda_ 128 _The Laurel_ 130 _Cross-fertilization of the Blue-flag_ 131 _Blue-flag_ 132 _Pogonia and Devil's-bit_ 133 _Devil's-bit_ 134 _Horse-balm. Collinsonia_ 135 _Cross-fertilization of the Horse-balm--Flowers in Various Stages, and in the Order of their Visitation by the Bee_ 136 _The Cone-flower_ 137 _Cone-flower, Showing Numerous Florets, Some in Pollen, Others in Stigmatic Stage_ 139 _Cross-fertilization of Cone-flower_ 140 _The Fertilization of the English Arum, 1st Stage_ 141 _The Fertilization of the English Arum. 2d, 3d, 4th, and 5th Stages_ 142 _Pogonia_ 145 _Cross-fertilization_ 146 _A Pine Branch_ 151 _Initial_ 151 _The Picnic_ 159 _Tail-piece_ 167