380 METHODS IN PLANT HISTOLOGY 



SCHIZOPHYCEAE 



4. Oscillatoria. — Fix in special chromo-acetic-osmic acid and stain in iron- 

 alum haematoxylin to show nuclei. Venetian turpentine method. 



5. Tolypothrix. — Use the Venetian turpentine method. Should show hetero- 

 cysts, hormogonia, and false branching. 



6. Nostoc. — Venetian turpentine method. 



7. Wasserbluthe. — -The principal forms in this material are: 



a) Coelosphaermm kutzingianum. — Colonies in the form of hollow spheres. 



b) Anabaena gigantea. — ^Filaments straight. Preparations should show 

 vegetative cells, heterocysts, hormogonia, and spores. 



c) Anabaena fios-aquae. — Filaments curved. Stain on the slide and mount 

 in balsam. If material is abundant, stain in iron-alum haematoxylin 

 and mount in Venetian turpentine. 



8. Gloeotrichia. — Smear on the slide, stain in safranin and gentian violet, 

 and mount in balsam; or use the Venetian turpentine method, staining in 

 phloxine and anilin blue and crushing under the cover glass. 



ALGAE 

 CHLOROPHYCEAE 



9. Volvox. — Use the Venetian turpentine method. If paraffin material is 

 available, cut 2-5 /x in thickness and stain in safranin, gentian violet, 

 orange. 



10. Scenedesmus. — Let a drop containing the material dry upon the slide, 

 stain, and mount in balsam. 



11. Hijdrodidyon. — ^Use the Venetian turpentine method. 



Each preparation should contain pieces of old and of young nets, and 

 also at least one young net developing within an older segment. The 

 greatest care must be taken not to injure the older segments while arrang- 

 ing the mount. 



12. Ulothrix. — Use the Venetian turpentine method. Each mount should 

 show various stages in the development of spores and gametes. 



13. Oedogonium. — Stain in phloxine and anihn blue and mount in Venetian 

 turpentine. 



14. Coleochaete. — Stain in Delafield's haematoxylin and mount in balsam. 



15. Cladophora. — Stain some in iron-haematoxylin and some in phloxine and 

 anilin blue. Mount both together in Venetian turpentine. 



16. Diatoms. — Make mounts of the frustules and also stained preparations 

 showing the cell contents. 



17. Desmids. — Make mounts of available forms. Use the Venetian turpen- 

 tine method if material is sufficiently abundant. 



18. Zygnema. — Stain in iron-haematoxylin and mount in Venetian turpen- 

 tine. 



19. Spirogyra. — Stain in phloxine and aniUn blue and mount in Venetian 

 turpentine. 



