Engelmann

• Engelmann was able to show that photosynthesis mainly used light from the red and blue parts of the spectrum 
• 1. He used filamentous alga spirogyra, a genus that has its chloroplasts arranged in a spiral pattern
• 2. He also used motile, aerobic bacteria as the bacteria is most likely to cluster in oxygen rich regions, where the rate of photosynthesis is higher 
• 3. He passed a light through a prism, separating light into different wavelengths onto the spirogyra in the presence of the bacteria
• 4. He concluded that the bacteria being aerobically accumulated in greater numbers around the parts of the chloroplasts that photosynthesised at the faster rates and therefore produced more oxygen
• 5. The cells and the chloroplasts in the red and blue light were photosynthesising at the fastest rate, showing the alga could utilise the red and blue part of the spectrum but green light was less readily absorbed