| Chapter III. The Distribution of Sexes | 5927 |
| Chapter XII. The Halicti: a Parasite | 6426 |
| Chapter VIII. Parasites | 6347 |
| Chapter IX. The Theory of Parasitism | 7171 |
| Chapter X. The Tribulations of The Mason Bee | 8062 |
| Chapter III. Another Prober (Perforator) | 6971 |
| Chapter XVI. A Parasite of The Maggot | 7344 |
