| Chapter III. The Distribution of Sexes | 4472 |
| Chapter XII. The Halicti: a Parasite | 4927 |
| Chapter VIII. Parasites | 4903 |
| Chapter IX. The Theory of Parasitism | 5810 |
| Chapter X. The Tribulations of The Mason Bee | 6413 |
| Chapter III. Another Prober (Perforator) | 5538 |
| Chapter XVI. A Parasite of The Maggot | 6020 |
