| Chapter III. The Distribution of Sexes | 5756 |
| Chapter XII. The Halicti: a Parasite | 6232 |
| Chapter VIII. Parasites | 6165 |
| Chapter IX. The Theory of Parasitism | 7017 |
| Chapter X. The Tribulations of The Mason Bee | 7881 |
| Chapter III. Another Prober (Perforator) | 6809 |
| Chapter XVI. A Parasite of The Maggot | 7153 |
