Bristol . — Life-history and Cytology of Chlorochytrium grande . 1 2 5 
Phyllobium sphagnicola is a coenocyte containing a reticulate mass of 
cytoplasm in which are embedded numerous small granules of chromatin 5 
and in the meshes of which there are a very large number of pyrenoids. 
The chlorophyll is probably diffuse throughout the cytoplasm. The cells 
of the branching thallus appear to have no contents. 
In conclusion I wish to express my thanks to Prof. G. S. West for pro- 
viding the material for this work, and for much help and criticism during the 
course of the investigation. 
The Botanical Laboratory, 
University of Birmingham. 
DESCRIPTION OF PLATES V AND VI. 
Illustrating Miss Bristol’s paper on Chlorochytrium grande. 
PLATE V. 
Chlorochytrium grande. All figures x 535, except Fig. 11. 
Figs. 1 and 2. Surface view of vegetative cells, showing lobed appearance of chloroplast. 
Fig. 3. Cell with apparent parietal chloroplasts, each with an internal projection (probably due 
to vacuolation of the cytoplasm). 
Figs. 4-6. Median sections of vegetative cells, showing rays in the cytoplasm ; Figs. 4 and 5 
through the nucleus and Fig. 6 through a central cluster of pyrenoids. 
Fig. 7. Non-median section, showing cytoplasmic rays cut transversely and obliquely, and 
numerous small pyrenoids. 
Fig. 8. Section through periphery of cell, showing cut ends of rays with deeply-staining sub- 
stance between. 
Fig. 9. Section of living cell, cut with a freezing microtome, showing distribution of chlorophyll 
(dark), with a colourless nucleus and peripheral layer of cytoplasm. 
Fig. 10. Section cut through a living cell, treated with osmic acid to show oil-drops. 
Fig. 11. Pyrenoids with starch-sheaths, and fragmenting pyrenoids. x 825. 
Fig. 12. Section of zoogonidangium, showing internal cellulose projection from the wall and 
corresponding depression in the cytoplasm, with the nucleus lying close to its side. 
Fig. 13. Section of small zoogonidangium with two cellulose projections from the wall. 
Fig. 14. Section of zoogonidangium with wall enormously thickened on one side but with no 
internal projection. 
Figs. 15 and 16. Sections of zoogonidangia with cytoplasm displaced by branched or twisting 
projections from the wall. 
Figs. 17-20. Multiplication by zoogonidia. 
Fig. 17. Small zoogonidangium in 16- celled stages of division. 
Fig. 18. The same cell after 3 hours. 
Fig. 19. The same cell after 17 hours, v. vesicle. 
Fig. 20. Zoogonidangium with escaping zoogonidia and a very long internal projection from 
the wall* 
