912.] The Life-history of Cladothrix dichotoma (Cohn). 357 



EXPLANATION OF PLATE, 

 igs. 1, 2. — Cladothrix cells enclosed in hardened mucilaginous sheath, x 2000. 

 Fig. 3. — Colony showing false dichotomy, x 125. 



4. — Cladothrix threads enclosed in unhardened mucilage, x 500. 



5. — Thread with hardened ruptured mucilage and from which most of the cells have 

 escaped, x 1000. 



6. — Portion of thread containing transverse bars of hardened mucilage, x 3000. 



7. — A portion of thread stained with iodine, showing transverse bars and glycogen 

 reserve material, x 3000. 



8. — Old threads, showing transverse bars of mucilage, and disorganised cells, 

 x 3000. 



9. — One cell, enclosed in hardened mucilaginous sheath, showing gaps in cytoplasm, 

 originally occupied by food material, x 2000. 



10. — Sheath showing at a and b broad transverse bars of mucilage. The mucilage 

 has tilled up spaces originally occupied by cells, x 1500. 



11. — Two cells showing reserve material in form of oil drops. x3000. 



12. 13. — Cells, stained with iodine, showing reserve food in form of glycogen. 

 X3000. 



, 14. — Portion of thread containing one cell, stained with iodine, and showing reserve 

 food in the form of oil drops and glycogen. The glycogen is superimposed 

 on the oil drops, x 3000. 

 15. — Old thread, the cytoplasm of which has almost entirely disappeared. Cell walls 

 are less completely disorganised. Well adapted to show stages of cell- 

 division, x 2000. 



, 16. — Somewhat diagrammatic representation of parent-thread to which a daughter- 

 thread is attached, x 3000. 



17. — Portion of thread showing two cells, derived by division of a single cell, still 

 connected by a band of mucilage, though a third of their length apart, 

 x 1000. 



18. — Thread from which the cells are in process of being liberated through the 

 ruptured apex, x 1000. 



19. — Colony of Cladothrix threads in artificial nutrient solution. Whole forms a 

 minute gray speck, visible to the naked eye, floating near the surface of the 

 liquid, x 100. 



20—22. — Spiral fragments of Cladothrix, showing polar ciliation. The spiral thread 

 in fig. 20 is composed of five cells, in fig. 21 of one cell, and in fig. 22 of seven 

 cells, x 1500. 



„ 23.— Spirally twisted cell with polar ciliation, liberated laterally from a Cladothrix 

 thread, x 1000. 



„ 24. — A spiral fragment liberated sideways from a Cladothrix thread, x 1500. 



„ 25. — Cilia preparation of threads from an artificial culture. Threads were in a state 

 of violent trembling as a result of the liberation of spirally twisted and 

 polar ciliated threads. At a is shown a cell on point of liberation, which 

 has elongated slightly, become spirally twisted, and polar-wise ciliated after 

 liberated from thread, x 1000. 

 , 26. — Liberated cell, showing a comparatively large number of polar cilia, x 1000. 



„ 27. — Newly liberated motile straight rod cells. X1000. 



, 28. — Newly liberated straight thread fragment. The cells of which it is composed 

 possess polar cilia, x 1000. 



