PLATE 39.— Opaque and Polarizing Objects. 



Figure 



1. Two rhombs of selenite as seen under different relative positions of the polarizer 



and analyzer. 



2. Crystals of acetate of copper (Acetic acid, Dichhoism). 



3. Crystals of uric acid under polarized light, natural and artificial (compare PI. 12). 



4. Prisms of ammonio-phosphate of magnesia, under polarized light. 



5. Ellipsoidal-constricted, or dumb-bell crystals of oxalate of lime, under polarized 



light. 



6. Crystals of oxalate of soda, under polarized light. 



7. Crystals of oxalate of ammonia, under polarized light. 



8. Crystals of oxalate of chromium and ammonia, under polarized light. 



9. Crystals of salicine, under polarized light. 



10. Crystals of sulphate of cadmium, under polarized light. 



11. Crystals of oxalurate of ammonia, under polarized light. 



12. Crystals of oxalurate of ammonia, under polarized light with a plate of selenite. 



13. Elytrum of Curculio imperialis, as an opaque object. 



14. Seed of white poppy (Papaver somniferum), opaque object. 



15. Seed of sweet-william (Dianthus barbatus), opaque object. 

 ift "i 



-ii-f \ Seeds of Silene gallica, opaque objects. 



18. Seeds of foxglove (Digitalis purpurea), opaque objects. 



19. Egg of puss-moth (Centra vinula), opaque object. 



20. Eggs of bug (Cimex lectularius), opaque objects ; the lids are removed. 



21. Eggs of Pontia rapce, opaque objects. 



22. Skin and scales of sole (Solea vulgaris), opaque objects. 



23. ffliopalocanium ornatum. 



24. Stephanastrum rhombus. 



25. Eucertydium ampulla, front view. 



26. Eucertydium ampidla, under view. 



27. Podocyrtis Schomburgkii. 



28. Anthocyrtis mespilus. 



29. Astromma Aristotelis. 



30. Lychnocanium lucerna. 



31. Haliomma Humboldtii. 



32. Eggs of Pontia brassicce, opaque objects. 



33. Portion of liver of cat ; the porta injected with red, the vena cava with yellow ; 



opaque object. 



34. Portion of lung of toad ; opaque object. 



35. Kidney of pig ; arteries and Malpighian bodies red, urinary tubules white ; 



opaque object. 



36. Spiracle of Bombyx, opaque object. 



37 1 



no \ Sections of Phinoceros-horn, by polarized light. 



39. White hairs of horse, interlaced ; by polarized light. 



40. Tous-les-mois starch, by polarized light with plate of selenite. 



)>Polyctstina. Opaque objects. 



