| Chapter III. The Distribution of Sexes | 5880 |
| Chapter XII. The Halicti: a Parasite | 6374 |
| Chapter VIII. Parasites | 6293 |
| Chapter IX. The Theory of Parasitism | 7125 |
| Chapter X. The Tribulations of The Mason Bee | 8013 |
| Chapter III. Another Prober (Perforator) | 6927 |
| Chapter XVI. A Parasite of The Maggot | 7295 |
