Saxton.—Contributions to the Life-History of Callitris, 569 
Fig. 3. Transverse section of mature microsporophyll, showing three microsporangia, resin cavity, 
and vascular bundle, x 40. 
Fig. 4. Longitudinal section of a young ovule, almost in the plane of the wing. [Wing partly 
cut on right, missed on left, of figure.] x 58. 
Fig. 5. Part of Fig. 4, showing the two megaspore mother-cells, x 930. 
Fig. 6. A somewhat later stage showing the functional megaspore, one disorganizing megaspore 
above and two below, and the non-functional mother-cell below these, x 930. 
Fig. 7. Median longitudinal section of the nucellus of an abortive ovule. About same age as 
Fig. 8. x 135. 
Fig. 8. Median longitudinal section of normal nucellus after first division of megaspore nucleus. 
[cf.Fig.7.] x 135. 
Fig. 9. Development of two embryo-sacs. x 400. 
Fig. 10. Embryo-sac with 16 nuclei, and 3 disorganizing megaspores below, x 230. 
Fig. 11. Sketch of nucellus in longitudinal section when 128 nuclei are present in the embryo- 
sac, showing positions of pollen-tube, embryo-sac and ‘ pavement tissue ’. x 40. 
Fig. 12. Longitudinal section of upper two-thirds of prothallus, showing position of pollen-tube 
and archegonia. Two adjacent archegonia near the base have just been fertilized, x 58. 
Fig. 13- Mature archegonium. The neck-cells have broken down, and the archegonium opens 
directly into the pollen-tube, x 930. 
Fig. 14. Microspore mother-cells connected to form a net-work, x 930. 
Fig. 15. Tip of fairly young pollen-tube. X 400. 
Fig. 16. Contents of tip of mature pollen-tube, x 545. 
Fig. 17. Archegonium after fertilization. [One of the archegonia of Fig. 12.] x 545. 
Fig. 18. Two adjacent mature proembryos, in nearly median longitudinal section, x 400. 
Fig. 19. Tangential section of a similar proembryo, x 400. 
Fig. 20. Dividing sporophyte nucleus. Not all chromosomes shown, x 1,500. 
Fig. 21. Dividing gametophyte nucleus from same series of sections. Not all chromosomes 
shown, x 1,500. 
Fig. 22. Part of a single proembryo in longitudinal section, x 570. 
Fig. 23. A suspensor bearing a four-celled (two in section) embryo, x 400. 
Fig. 24. Multinucleate prothallus cells on the border of the starch-containing region. 
Fig. 25. Tip of abnormal pollen-tube, x 135. 
PLATE XLVI. 
Fig. 1. Longitudinal section of seed, showing embryo with cotyledons differentiated. 
Fig. 2. Transverse section of seedling, showing cotyledons and plumular leaves. 
Fig. 3. Longitudinal section of ovule, containing prothallus. 
