| Chapter III. The Distribution of Sexes | 3723 |
| Chapter XII. The Halicti: a Parasite | 4155 |
| Chapter VIII. Parasites | 4148 |
| Chapter IX. The Theory of Parasitism | 5042 |
| Chapter X. The Tribulations of The Mason Bee | 5618 |
| Chapter III. Another Prober (Perforator) | 4908 |
| Chapter XVI. A Parasite of The Maggot | 5336 |
