PLATE 31. — Opake and Polarizing Objects. 



Figure 



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



and analyser. 



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



3. Crystals of uric acid under polarized Kght, natural and artificial (compare PL 8). 



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. Crystal of salicine, under polarized light. 



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



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



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



13. Elytrum of Curcidio hnperialis, as an opake object. 



14. Seeds of white poppy {Papaver somnifenim), opake object. 



15. Seed of sweet-william {Dianthus fasciculatus), opake object. 



, y \ Seeds of Silene gallica, opake objects. 



18. Seeds of foxglove {Digitalis imrpurea), opake objects. 



19. Egg of puss-moth {Cerura vinuld), opake object. 



20. Eggs of bug {Cimex lectularius), opake objects ; the lids are removed. 



21. Eggs oi Pontia rapce, opake objects. 



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



23. Rhop)alocanium ornatum. 



24. Stephanastrum rhombus. 



25. Eucertydium ampulla, front view. 



26. Eucertydium ampulla, under view. 



27. Podocyrtis Schomburgkii, 



28. Anthocyrtis mespilus. 



29. Astromma Aristotelis. 



30. Lychnocardum lucerna. 



31. Haliomma Humboldtii. 



32. Eggs of Pontia brassicce, opake objects. 



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



cava mth yellow ; opake object. 



34. Portion of lung of toad ; opake object. 



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



object. 



36. Spiracle of Bombyx, opake object. 



37 1 . . 



oo* ? Sections of Rhinoceros's horn ; by polarized light. 



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



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



' PoLYCYSTiNA. Opake objects. 



