6 04 
Saxton. — Contributions to the 
EXPLANATION OF FIGURES IN PLATES XLIV-XLVI. 
Illustrating Professor Saxton’s paper on Tetraclinis. 
Note. — In the Plates all figures of longitudinal sections are oriented with the longer axis of the 
ovule vertical and the micropylar end upwards. 
In all : a = archegonium ; b = body-cell ; c = micropyle closing cells ; d = functional mega- 
spore mother-cell ; e = egg nucleus ; f — sterile nuclei of the pollen-tube ; g — generative cell ; 
h *= tapetal cells ; k = tube nucleus ; m = male cells ; n = neck-cells ; p = functional megaspore ; 
q non-functional megaspore ; s = starch sheath ; sp = sporogenous tissue ; t = pollen-tube ; 
v « ventral canal nucleus ; <5 = male nucleus ; ? = female nucleus. 
PLATE XLIV. 
Figs. 1-26. Various stages in the development of the microspores from the microspore mother- 
cell. All except Fig. 24 drawn from sections of fixed material, and x 1300; Fig. 24 drawn from 
fresh material, and x 600. All from material collected April 24-30, 1912. 
Fig. 27. Germinating pollen-grain, with generative cell and tube nucleus, x 600. May 18. 
Fig. 28. Slightly older pollen-tube, with generative cell and tube nucleus; reconstructed from 
serial sections. X 600. May 11. 
Fig. 29. Tip of older pollen-tube, with body-cell nucleus and two sterile nuclei ; from two 
adjacent sections, x 600. May 18. 
Fig. 30. The tip of a pollen-tube shortly before the body-cell divides, x 600. June 28. 
Fig. 31. Median longitudinal section of young ovule, just before pollination, x 160. April 24. 
Fig. 32. The sporogenous tissue of the same ovule more highly magnified, x 600. 
Fig- 33- The tip of the nucellus of a slightly older ovule, showing the characteristic breaking 
down of the apical cells, x 160. April 27. 
Fig. 34. Longitudinal section of the tip of an ovule just after pollination, to show the micropyle 
closing cells, x 160. May 11. 
Fig. 35. Transverse section of the same, x 160. April 27. 
Fig. 36. Megaspore mother-cell and surrounding tissue, x 600. May 18. 
Fig. 37 • Functional and non -functional megaspores, and tapetum. x 370. Drawn from two 
adjacent sections. April 29. 
Fig. 38. One of the thirty-two dividing nuclei in a young embryo-sac. x 1,100. May 18. 
PLATE XLV. 
Fig. 39. Apex of a prothallus in longitudinal section, showing the archegonium initials, 
x 250. August 12. 
Fig. 40. Very young archegonia, with primary neck-cells; drawn from several serial sections, 
x 370. July 30. 
Fig. 41. Longitudinal section of archegonial complex, and two pollen-tubes; reconstructed 
from several serial sections, x 160. Sept. 11. 
Fig. 42. Part of a similar section to Fig. 41 ; drawn from several serial sections. x 370. 
Sept. 11. 
Fig. 43. Part of archegonium, showing ventral canal nucleus recently cut off. x 530. Sept. 11. 
Fig. 44. The same, a little later, x 530. Sept. 11. 
Fig. 45. The neck of an archegonium from Fig. 41, in longitudinal section, x 530. 
Fig. 46. Transverse section through the neck of a mature archegonium. One nucleus was 
present in the next section, which has not been represented in the figure, x 530. Sept. 11. 
Fig. 47. Fertilization. Male nucleus above, x 530. Oct. 3. 
Fig. 48. The same. Male nucleus below, x 530. Sept. 23. 
Fig. 49. The fusion nucleus, x 530. Sept. 23. 
