| Chapter III. The Distribution of Sexes | 5934 |
| Chapter XII. The Halicti: a Parasite | 6432 |
| Chapter VIII. Parasites | 6362 |
| Chapter IX. The Theory of Parasitism | 7178 |
| Chapter X. The Tribulations of The Mason Bee | 8071 |
| Chapter III. Another Prober (Perforator) | 6981 |
| Chapter XVI. A Parasite of The Maggot | 7353 |
