| Chapter III. The Distribution of Sexes | 3567 |
| Chapter XII. The Halicti: a Parasite | 3974 |
| Chapter VIII. Parasites | 3966 |
| Chapter IX. The Theory of Parasitism | 4819 |
| Chapter X. The Tribulations of The Mason Bee | 5432 |
| Chapter III. Another Prober (Perforator) | 4769 |
| Chapter XVI. A Parasite of The Maggot | 5176 |
