| Chapter III. The Distribution of Sexes | 3925 |
| Chapter XII. The Halicti: a Parasite | 4394 |
| Chapter VIII. Parasites | 4354 |
| Chapter IX. The Theory of Parasitism | 5397 |
| Chapter X. The Tribulations of The Mason Bee | 5834 |
| Chapter III. Another Prober (Perforator) | 5103 |
| Chapter XVI. A Parasite of The Maggot | 5533 |
