LIST OF ILLUSTRATIONS 



Transverse section of beech twig . . . Frontispiece 



1. Unicellular plants multiplying ..... 3 



2. Desmids (Closterium lumila) 5 



3. Desmids (Micrasterias denticulata) ..... 7 



4. Diatoms grouped ........ 10 



5. Diatoms on a dark ground ...... 12 



6. Diatoms dredged from the Atlantic .... 14 



7. Diatoms common in ponds and lakes . . . . 15 



8. Diatom-chains ........ 16 



9. Selected diatom (Araclmoidiscus Ehrenbergii] . . 17 



10. Central portion of diatom group, Fig. 4 18 



11. Selected diatoms from group, Fig. 10 . . . . 19 

 12 Selected diatoms from group, Fig. 4 .... 20 



13. Artistic arrangement of diatoms ..... 21 



14. Central portion of diatom group, Fig. 13 . . . 23 



15. Another artistic arrangement of diatoms ... 24 



16. Central portion of group, Fig. 15 ..... 26 



17. Thread-like plants (Spirogyra) 28 



1 8. Volvox globator ........ 29 



19. Freshwater alga (Draparnaldia) ..... 30 



20. Freshwater alga (Batraclwspermuni) . . . . 31 



21. Alga on damp fence ....... 33 



22. Vegetable cells of apple 35 



23. Hairs from flower of pansy ...... 37 



24. Cells from surface of geranium petal .... 38 



25. Scales from fern frond ....... 39 



26. Vascular tubes in stem of bracken fern ... 40 



