| Chapter III. The Distribution of Sexes | 4811 |
| Chapter XII. The Halicti: a Parasite | 5230 |
| Chapter VIII. Parasites | 5243 |
| Chapter IX. The Theory of Parasitism | 6116 |
| Chapter X. The Tribulations of The Mason Bee | 6793 |
| Chapter III. Another Prober (Perforator) | 5847 |
| Chapter XVI. A Parasite of The Maggot | 6318 |
