| Chapter III. The Distribution of Sexes | 4694 |
| Chapter XII. The Halicti: a Parasite | 5135 |
| Chapter VIII. Parasites | 5134 |
| Chapter IX. The Theory of Parasitism | 6023 |
| Chapter X. The Tribulations of The Mason Bee | 6674 |
| Chapter III. Another Prober (Perforator) | 5754 |
| Chapter XVI. A Parasite of The Maggot | 6230 |
