115 
Description of Plates 295, 296. 
Figures 1-18 are stages in Preris; figures 19-21 are Adiantum; all figures are 
drawn with a Zeiss Camera lucida, : 
Fig. 1. Early sporocytes in the resting stage subsequent to the last division of 
the archesporial cells. >< 1800, 
Fig. 2. Primary sporocyte after growth. Chromatin arranged in a delicate, 
single, moniliform spireme, nucleolus persistent. >< 1800, 
Fig. 3. Primary sporocyte with thickened and concentrated spireme. The end 
(x) is double. >< 1800, 
Fig. 4. Primary sporocyte showing different stages in tetrad formation, C-ring 
forms. >< 1800. : 
Fig. 5. Primary sporocyte; portion of nucleus showing stages in tetrad formation. 
A-double spireme segment; C-ring forms; X-divergent forms, >< 2300. 
Fig. 6. Various types of tetrad formation; A, B, C, F, G, H, K, L, show the 
“ cross type,” Dand E the * rod type,” I and J the “ ring type.” >< 3600. 
Fig. 7. Primary sporocyte with finished tetrads. > 1800. 
Fig. 8. Primary sporocyte showing spindle fibres, loss of nuclear membrane, and 
distribution of the tetrads. .< 2300. : 
Fig. 9. Primary sporocyte section showing fewer tetrads and the arrangement on 
the spindle fibres. >< 2300. 
Fig. 10. Primary sporocyte, a prophase showing concentration of the tetrads into 
the nuclear plate. >< 2300. 
Fig. 11, Primary sporocyte; metaphase showing completed spindle. C-centro- 
some. >< 2300, 
Fig. 12. Primary sporocyte, anaphase showing division of tetrads into dyads. 
D-dyads. C-centrosome. > 1800. 
Fig. 13. Secondary sporocyte; metaphase showing arrangement of elongate dyads 
in the nuclear plate. C-centrosome. 1800. 
Fig. 14. Late anaphase of the division of the secondary sporocyte showing the four 
nuclei free in the cell, with connecting spindle fibres, >< 2300. . 
Fig. 15. Early spores. The cell plates have formed; remnants of the spindle 
fibres can still be seen. >< 1800. 
Fig. 16. Young spore, Nucleoli have reappeared, >< 1800. 
Fig. 17. Primary archesporium; a few of the chromosomes during the early stage 
of division, They are distinctly double. >< 2300. 
Fig. 18. Somatic cell from a young fern plant, in division. >< 2300. 
Fig. 19. Primary sporocyte (Adiantum) showing formation of tetrads. C-ring 
form. A-cross form. >< 2300. 
Fig. 20. Primary sporocyte showing division of tetrads into the nuclear plate. 
C-ring forms, >< 2300. 
Fig. 21. Primary sporocyte showing division of the tetrads to form dyads. (D). 
X 2300. 
