M. Miiller on the Germination of Isoetes lacustris. 329 



Fig. 12. Further stage, a. Alimentary organ, b. Radical portion, c. Mother- 

 cell of the second leaflet, d. Vagina, e. First leaf. /. Cell of 

 the first scale. 



— 13. The same, drawn from the face. a. A cell which is the support of 



the cell of the first scale, b. Mother-cell of the second leaflet. 

 c. Cells of the vagina, d. Cell of the first scale. 



— 14. Ovule bursting open. a. Primine. b. Secundine. c. Nucleus. 



— 15. a. Ovule, when the young embryo has just broken through the apex 



of the coat of the nucleus; the young embryo shines through, of 

 a green colour, at the summit of the coat of the nucleus, b. The 

 young embryo extracted, c. Alimentary organ, d. Cell of the first 

 scale, e. Mother-cell of the second leaflet. /. Radical portion. 

 g. Vagina. 



— 16. a. Ovule, when the embryo has entirely broken through the apex 



of the coat of the nucleus and issued all except the germinal body 

 (pro-embryo), b. The little plant extracted : this is otherwise 

 not normally formed : the alimentary organ and radical portion are 

 not yet visible, c. First scale, d. Cell of the second leaflet. 



— 17. a. Embryo elongating by the expansion of its cells, extruded from 



the coat of the nucleus as far as the germinal body. b. The same 

 magnified 250 times, c. First scale, d. Second leaflet, <?. Root. 

 /. Alimentary organ, g. Outermost portion of the root, in the cells 

 of which all the contents have become fluid and transparent. 



— 18. a. Embryo of the natural size. b. 250 times enlarged, d. Ali- 



mentary organ, e. Apex of the root. /. Vessels, g. Epidermoid 

 outermost layer of cells of the root, with cytoblasts. h. First scale. 

 i. Cells of the vagina, k. Second leaf. 



— 19. a. Two embryos in a single ovule, of natural size. b. Magnified 



20 times, c Magnified 50 times, d d. Second leaflets, e e. Empty 

 alimentary organs. 



— 20. a. Embryo, nat. size, when the root breaks through the lowermost 



part of the coat of the nucleus, b. Magnified 50 times with g, 

 the extruded root. c. Extracted, d. Second leaf. e. First scale. 

 /. Alimentary organ, h. Vagina. 



— 21. a. Embryo prepared free from the ovule; 50 times enlarged. 



b. Spiral vessel, 400 times enlarged, c. Alimentary organ, df. Se- 

 cond leaflet, e. Point of vegetation on the apex of the root. 

 /. End of the spiral vessel in the root. g. Vagina. 



— 22. c. Empty alimentary organ, d. Vagina, e. Second leaflet. f. 



Second radical portion. 



— 23. a. Embryo, nat. size. b. Magnified 50 times, c. Empty alimen- 



tary organ, d. Vagina, e. Second root. 



— 24. Development of an individual up to the formation of the third 



leaflet, a. First leaf. b. Second leaf. e. Third leaf. d. The 

 same magnified 50 times with x, the third leaf. e. The stage when 

 the plants died : first root gone. /. First root and first leaf gone. 

 g. First root, first leaf and second root gone. 



— 25. Germinating plant of Selaginella. a. Germinal body (pro-embryo). 



b. Radical portion, c. Terminal bud. d. Granular contents of 

 the ovule. 



Ann. 2$ Mag. N. Hist. Ser. 2. Vol ii. 23 



