| Chapter III. The Distribution of Sexes | 3843 |
| Chapter XII. The Halicti: a Parasite | 4296 |
| Chapter VIII. Parasites | 4270 |
| Chapter IX. The Theory of Parasitism | 5262 |
| Chapter X. The Tribulations of The Mason Bee | 5748 |
| Chapter III. Another Prober (Perforator) | 5016 |
| Chapter XVI. A Parasite of The Maggot | 5447 |
