Subjects
- Malaria.1
- Mosquitoes -- Control.1
- Mosquitoes.1
- Natural resources.1
- Nematodes.1
- Picnics.1
- Plant diseases.1
- Professors.1
- Research.1
- Rivers.1
- Scientific expeditions.1
- Scientists.1
- Ships.1
- Snakes.1
- Spiritualism -- United States -- History -- 19th century.1
- Students -- Massachusetts -- Cambridge.1
- Sugar cane -- Hawaii.1
- Teaching methods.1
- Technological innovations -- United States.1
- Television in education.1