| Chapter III. The Distribution of Sexes | 4335 |
| Chapter XII. The Halicti: a Parasite | 4784 |
| Chapter VIII. Parasites | 4750 |
| Chapter IX. The Theory of Parasitism | 5681 |
| Chapter X. The Tribulations of The Mason Bee | 6238 |
| Chapter III. Another Prober (Perforator) | 5422 |
| Chapter XVI. A Parasite of The Maggot | 5912 |
