| Chapter III. The Distribution of Sexes | 5623 |
| Chapter XII. The Halicti: a Parasite | 6090 |
| Chapter VIII. Parasites | 6028 |
| Chapter IX. The Theory of Parasitism | 6902 |
| Chapter X. The Tribulations of The Mason Bee | 7736 |
| Chapter III. Another Prober (Perforator) | 6688 |
| Chapter XVI. A Parasite of The Maggot | 7040 |
