| Chapter III. The Distribution of Sexes | 4957 |
| Chapter XII. The Halicti: a Parasite | 5347 |
| Chapter VIII. Parasites | 5378 |
| Chapter IX. The Theory of Parasitism | 6242 |
| Chapter X. The Tribulations of The Mason Bee | 6954 |
| Chapter III. Another Prober (Perforator) | 5970 |
| Chapter XVI. A Parasite of The Maggot | 6425 |
