Fig. 40. THIN DISC OF COW'S MILK, THE 120TH OF AK INCH IN DIAMETER, MAGNIFIED 

 400 TIMES IN ITS LINEAR, AND 160000 TIMES IN ITS SUPERFICIAL DIMENSIONS. 



MICROSCOPIC DRAWING & ENGRAVING. 



CHAPTEE IV. 



64. Structure of the itch insect. 65. Its habits. 66. The mange insect. 

 67. Its form and structure. 68. Defects incidental to drawing 

 with the camera. 69. Microscopic photographs. 70. Microscopic 

 daguerreotypes % Messrs. Donne and Foucault. 71. Description of 

 the blood. 72. Red and white corpuscles. 73. Daguerreotype of 

 a drop of blood magnified. 74. Magnitude of the corpuscles. 75. 

 Cause of the redness of blood. 76. Corpuscles of inferior animals. 

 77. White globules. 78. White grains. 79. White globules con- 

 verted into red corpuscles. 80. Red corpuscles dissolved. 81. 

 Circulation of the blood. 82. Method of showing it in the tongue 

 of a frog. 83. The arteries distinguishable from the veins. 84. The 

 vascular system of the tongue. 85. Mucous glands. 86. Milk ; its 



LARDNER'S MUSEUM OF SCIENCE. H 97 



