LIST OF FIGURES 



Figure Page 



1. Launch and plankton apparatus 10 



2. Pumping apparatus 10 



3. Sketch, of lakeside laboratory showing centrifuge 13 



4. Sectional view of bowl of centrifuge 14 



5. Launch with a cargo of water 14 



6. Map of four lakes region 21 



7. Organic matter in net plankton of Lake Mendota, 1911-14 26 



8. Organic matter in net plankton of Lake Mendota, 1915-17 29 



9. Nitrogen of net plankton, 1911-12 33 



10. Nitrogen of net plankton, 1913-15 34 



11. Organic matter, crude protein, and ether extract of net plankton of 



Lake Mendota, 1911 36 



12. Organic matter, crude protein, and ether extract of net plankton of 



Lake Mendota, 1912 37 



13. Organic matter, crude protein, and ether extract of net plankton of 



Lake Mendota, 1913-14 38 



14. Organic matter, crude protein, and ether extract of net plankton of 



Lake Mendota, 1915 39 



15. Organic matter and ash of net plankton of Lake Mendota, 1911 46 



16. Organic matter and ash of net plankton of Lake Mendota, 1912 47 



17. Organic matter and ash of net plankton of Lake Mendota, 1913 48 



18. Organic matter and ash of net plankton of Lake Mendota, 1914 49 



19. Organic matter and ash of net plankton of Lake Mendota, 1915 50 



20. Organic matter and ash of net plankton of Lake Mendota, 1916-17. ... 51 



21. Diagram illustrating construction of spherical type of curve 59 



22. Numerical results for net plankton of Lake Mendota, 1911 60 



23. Numerical results for net plankton of Lake Mendota, 1912 60 



24. Numerical results for net plankton of Lake Mendota, 1913 61 



25. Numerical results for net plankton of Lake Mendota, 1915 62 



26. Numerical results for net plankton of Lake Mendota, 1916-17 62 



27. Photograph of dry nannoplankton material obtained in 1917 66 



28. Organic matter in nannoplankton of Lake Mendota, 1915-17 68 



29. Nitrogen in nannoplankton of Lake Mendota, 1915-17 72 



30. Organic matter, crude protein, and ether extract in nannoplankton of 



Lake Mendota, 1915 76 



