44 BOTANICAL GAZETTE {jury 
19. Norén, C. O., Ueber die Befruchtung bei Juniperus communis. Arkiv Bot. 
3:1-11 (No. 11). 1904. 
20. ———, Zur Entwicklungsgeschichte des Juniperus communis. Uppsala 
Universitets Arsskrift 1-64. 190 
21. RENNER, O., Ueber Zwitterbliiten bei Juniperus communis. Flora 93:297- 
300. 1904. 
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Deutsch. Bot. Gesells. 23: 335-346. 1905. 
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quelques gymnospermes. Bull. Soc. Imp. Nat. Moscou. 1880. 
24. STRASBURGER, E., Die Befruchtung bei den Coniferen. pp. 22. Jena. 1869. 
, Die Coniferen und die Gnetaceen. pp. 442. Jena. 1872. 
26. —_——,, Die Angiospermen und die Gymnospermen. pp. 173. Jena. 1879. 
, Ueber das Verhalten des Pollens und die Befruchtungsvorgange bei 
den loa. Hist. Beitr. 4:1-156. 1892 : 
28. Tomson, R. B. The megaspore membrane of the gymnosperms. Univ. 
Toronto Biol. Series 4:1-54. 1905. 
. WesseR, H. J., Spermatogenesis and fecundation of Zamia. U. S. Dept. 
Agric., Bur. Pl. Indus. Bull. 11:1-86. rgor. 
EXPLANATION OF PLATES I—IV 
The figures were drawn with the aid of an Abbé camera lucida. The degree 
of magnification is indicated in the description of each figure. The following 
abbreviations are used in connection with the figures. Antheridial cell, a; arche- 
gonium, arch; archesporial tissue, a.¢; central cell, c; central nucleus, ¢. 2; cy! 
plasmic condensation, c. ¢; egg nucleus, e. 7; generative cell, g; inner wall, 7. 
integument, 7; micropyle, M; microspore mother cell, Mi. m.c; microsporan- 
gium, Mg; microsporophyll, Mp; nucellar cap, ”. c; neck cells, nk; nucellus, #¥é; 
outer wall, 0. w,; pollen chamber, ?. c; oo pro; protein vacuole, p- % 
starch, s; secondary nucleoli, s. mu; sperm c , Sp; sperm nucleus, s. 7; Sponsy — 
tissue, s.t; sheath cell, sh.c; stalk cell, st. c; galk nucleus, st. n,; tapetum, 
tube cell, ¢. c; tube nucleus, ¢. 2; ventral canal nucleus, v. ¢. ”. 
vv 
oO 
PLATE I 
Fic. 1.—Longitudinal section of staminate cone of J. communis; April 25) — 
1905. X62. 
Fic. 2.—Microsporangium of J. communis, showing microspore mother cells, 
tapetum, and wall; May 1, 1905. x 382. 
Fic. 3.—Mature microspore of J. communis, just before pollination. X 185% 
Fic. 4.—Pollen grain of J. communis, from the nucellus of an ovule, in pea 
phase of first division; May 26, 1905. 1850. 
Fic. 5.—A two-celled pollen grain of J. virginiana, two weeks after pollins = 
tion. 1850. 
Fic. 6.—Nucellar cap of J. virginiana, showing disintegration of cells 
beneath the pollen grain. X 116. 
