Embryo of Sciadopitys verticillata. 419 
Miyake, K. (’ 03 ): Contribution to the Fertilization and Embryogeny of Abies balsama. Beihefte 
zum Bot. Cent., xiv, p. 134, 1903. 
Murrill, W. A. (’ 00 ): The Development of the Archegonium and Fertilization in the Hemlock 
Spruce ( Tsuga canadensis'). Ann. Bot., xiv, p. 583. 
Robertson, A. (’ 04 ): Spore formation in Torreya Californica. New. Phyt., iii, p. 133, 1904. 
- (’ 04 ): Studies in the Morphology of Torreya Californica. NevvPhyt., iii, p. 205,1904. 
Saxton, W. T. (’ 09 ): Preliminary Account of the Ovule, Gametophyte, and Embryo of Widdring- 
tonia cupressoides. Bot. Gaz., xlviii, no. iii, p. 166, 1909. 
Sokolowa, Mile C. (’ 90 ): Naissance de l’endosperme dans le sac embryonnaire de quelques 
Gymnospermes. Bull. Soc. Imp. Nat. Moscou, 1890 (1891), p. 446. 
Thomson, R. B. (’ 05 ): The Megaspore-membrane ot the Gymnosperms. Univ. Toronto Studies, 
Biol. Series, iv. 1905. 
EXPLANATION OF FIGURES IN PLATES XXIX-XXXI. 
Illustrating Dr. Lawson’s Paper on Sciadopitys. 
All figures were drawn with the aid of the camera lucida. The following oculars and 
objectives were used :— 
Figs. 1, 2, 3, 4, 5, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 
36, 38, Zeiss oc. 8, obj. -T oil imm. x about 1600. 
Figs. 14, 15, 45, 46, 47, 52, 53, 54, Zeiss oc. 4, obj. C. x about 250. 
Figs. 40, 41, 42, 43, 44, 48, Zeiss oc. 4, obj. A. x 100. 
Figs. 10, 11, 12, 37, 39, Zeiss oc. 4, obj. -£2 °il imm. x about 1000. 
Figs. 8, 9, 50, Zeiss oc. 8, obj. C. x about 450. 
Figs. 13, 49, Zeiss oc. 8, obj. A. x about 160. 
Fig. r. A cross section of a microspore some time before pollination, showing the single 
centrally situated nuclear considerably enlarged and preparing for mitosis. April 22. 
Fig. 2. The same at a later stage, showing the spindle of the first division of the microspore 
nucleus. This and the following two figures shows the characteristic hard thick exine tapering out 
and becoming very thin at one side. April 22. 
Fig. 3. The same, showing the chromosomes at the poles of the spindle. April 22. 
Fig. 4. The same, showing the daughter-nuclei fully organized and separated from one another 
by a very thin cell membrane. April 22. 
Fig. 5. A section of a microspore a few days after pollination, as seen at the surface of the 
pollen-cushion of the nucellus. Here the exine has been completely thrown off, and the spore itself 
has become elongated and considerably enlarged. The generative and tube-cells are fully 
developed. April 24. 
Fig. 6. A longitudinal section of a young ovule taken about three or four weeks after pollination, 
showing the integument and nucellus with the pollen-grains collected on the surface of the pollen- 
cushion. The micropyle has not yet been closed. May 25. 
Fig. 7. A longitudinal section of the upper part of the nucellus, showing the nature of the highly 
differentiated tissue of the pollen-cushion, into which the pollen-tubes are penetrating. July 17. 
Fig. 8. A longitudinal section of a pollen-tube after the division of the generative cell, showing 
the body-cell and the stalk-nucleus still in the spore region of the tube. June 17. 
Fig. 9. The same, showing the relative positions of the three essential structures of the tube. 
The body-cell has remained within the spore region of the tube. The stalk and tube nuclei have 
descended into the tube for a considerable distance, the latter in advance of the former. June 17. 
Fig. 10. The same, more highly magnified to show the structure of the nuclei and the presence 
of large masses of starch grains in the cytoplasm of the tube. July 17. 
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