Distinction between Parasites and Carnivora--Parasites found on all Classes of Animals--Males dependent on Females--Parasites on Man--Abundant Parasites in Stork-- All the Organs nourish Parasites--Different size of Male and Female--Lerneans--Diplozoa--Migration of Parasites--Corresponding Changes of Form--Parasites restricted to certain Regions--Former Theory of Spontaneous Generation 85 CHAPTER VI. PARASITES FREE DURING THEIR WHOLE LIFE. Leeches--Vampires--Cylicobdellæ--Branchellions--Gnats-- Blackflies--Mosquitoes--Gnats in high Latitudes--Tsetse-- Ox-flies--Pteropti--Nycteribiæ--Bugs-- Lice--Fleas--Itch Insect--Acari on Beetles and Bees--Cheyletus eruditus 107 CHAPTER VII. PARASITES FREE WHILE YOUNG. Isopod Parasites--Chigoe--Ticks--Pigeon-mite--Bopyridæ-- Ichthoxenus--Peltogasters--Tracheliastes--Penellæ-- Lerneans--Guinea-worm--Leptodera of Snail--Nematodes in Bones--Lichnophoræ--Gregarinæ 138 CHAPTER VIII. PARASITES THAT ARE FREE WHEN OLD. Utility of Ichneumons--Scoliæ of Tan-beetles--Scolyti of Seychelles Cocoa-nut Trees--Elms at Brussels destroyed by Scolyti--Polynema in Eggs of Dragon-fly--Sphex--Platygaster-- Horse-fly--Livingstone--Animals in Paraguay destroyed by ix Hippobosci--Dipterous Parasites on Sheep and Stag--Gordius-- Shower of Worms--Eels in Ears of Corn 162 CHAPTER IX. PARASITES THAT MIGRATE AND UNDERGO METAMORPHOSES. Nostosites--Xenosites--Hosts serving as a Crèche, a Vehicle, or a Lying-in Hospital--Lamarck on Spontaneous Generation--Trematodes--Monostomes--Sporocysts and Cercariæ--Passage from one Host to another--Distomes-- Flukes--Hemistomes--Amphistomes--Tæniæ of the Dog and Wolf--Hydatids--Tænia solium in Man--Cysticercus of Pig--Cysticercus of Rabbit and Hare passing into Dog-- Coenurus of Sheep--Bothriocephalus--Linguatula in Negro-- Strongyli--Trichinæ--Panic in Germany--Vibriones in Corn-- Echinorrhynchus--Dicyema 183 CHAPTER X. PARASITES DURING THEIR WHOLE LIFE. Strepsitera--Stylops--Rhipiptera--Tristomidæ--Epibdella-- Diplozoon, two Individuals--Polystomum of Frog--Gyrodactyles-- Cochineal Insect--Aphides--Phylloxera of Vine--An Acaris, its Mortal Enemy--Ant-Cows--Bonnet's Theory of Germs--The Reduvius personatus, a valuable enemy to the Bed-bug 255 LIST OF ILLUSTRATIONS. x FIG. PAGE