| Chapter III. The Distribution of Sexes | 5495 |
| Chapter XII. The Halicti: a Parasite | 5980 |
| Chapter VIII. Parasites | 5889 |
| Chapter IX. The Theory of Parasitism | 6774 |
| Chapter X. The Tribulations of The Mason Bee | 7603 |
| Chapter III. Another Prober (Perforator) | 6549 |
| Chapter XVI. A Parasite of The Maggot | 6922 |
