| Chapter III. The Distribution of Sexes | 5654 |
| Chapter XII. The Halicti: a Parasite | 6123 |
| Chapter VIII. Parasites | 6056 |
| Chapter IX. The Theory of Parasitism | 6929 |
| Chapter X. The Tribulations of The Mason Bee | 7769 |
| Chapter III. Another Prober (Perforator) | 6716 |
| Chapter XVI. A Parasite of The Maggot | 7067 |
