Actinostr obits pyramidalis , Miq. 343 
21. Saxton, W. T. : Contributions to the Life-history of Callitris. Ann. Bot. xxiv, 1910, pp. 
557-69, Pis. xlv, xlvi. 
22. : Note on an Abnormal Prothallus of Pinus maritima , L. Ann. Bot., vol. xxvi, 
19 * 2 > PP- 943-5* 
23. Seward, A. C., and Ford, S. O. : The Araucarieae, recent and extinct. Phil. Trans. Roy. 
Soc., London, B, vol. cxcviii, 1906, pp. 305-41 1, Pis. xxiii, xxiv. 
EXPLANATION OF FIGURES IN PLATES XXV-XXVIII. 
Illustrating Mr. Saxton’s paper on Actinostrobus . 
Note. All figures of longitudinal sections are oriented with the longer axis of the ovule vertical 
and the micropylar end upwards, except Figs. 36-43, which are with the longer axis of the ovule 
horizontal (approximately) and that of the archegonium vertical, with the apex of the archegonium 
upwards. The orientation of Figs. 53-56 (Plate XXVIII) is indicated by an arrow. 
In all : a = archegonium ; b — body cell ; c — micropyle closing cells, d ■■= megaspore mother* 
cell ; e = embryo cell ; f — neck cells ; g — secretory cavity ; h — sterile nuclei of the pollen- 
tube ; i = integument ; k = embryonal tubes (secondary suspensors) ; m = male cells ; n = nu- 
cellus ; p = prothallus ; s = suspensor ; t = pollen-tube ; v. = ventral nucleus ; = male nucleus ; 
? = female nucleus. 
PLATE XXV. 
Fig. r. Transverse section through the stalk of the microsporophyll. x 80. 
Fig. 2. Section of a mature pollen-grain, x 1,100. July 13. 
Fig. 3. Longitudinal section of a young ovule, before pollination, x 120. 
Fig. 4. Young megaspore mother-cell, in longitudinal section, x 550. June 1. 
Fig. 5. Megaspore mother-cell in synapsis, x 950. June 1. 
Fig. 6. Megaspore with remains of non-functional megaspores, x 950. 
Fig. 7. Binucleate megaspore, x 800. July 13. 
Fig. 8. Longitudinal section of a whole ovule at the time when the young embryo-sac contains 
eight nuclei, x 160. July 13. 
Fig. 9. Part of the prothallus in longitudinal section at the time when cell formation is taking 
place, x 200. Oct. 12. 
Fig. 10. Transverse section of prothallus, showing position of young archegonia and pollen- 
tubes. x 200. Oct. 12. 
Fig. 11. Transverse section of the neck of an archegonium. x 340. 
Fig. 12. Longitudinal section t>f part of a prothallus, showing three archegonia and the contents 
of a pollen-tube, x 340. Oct. 19. 
Fig. 13. Only case seen of an archegonium showing a ventral canal nucleus. (See text.) 
x 485. Oct. 14. 
Fig. 14. Abnormal archegonium. (See text.) x 450. Oct. 14. 
Fig. 15. Tangential section of part of a prothallus, cutting a single group of archegonia trans- 
versely. x 190. Oct. 12. 
Fig. 16. Transverse section of a prothallus, in which no pollen-tube was found, showing very 
deep-seated archegonia. x 100. Oct. 12. 
Fig. 17. Transverse section of an ovule, showing the structure of the integument, x 15. 
Fig. 18. Part of the same section, showing one of the secretory cavities on a larger scale, x 50. 
Fig. 19. Transverse section of a nucellus and prothallus. x 24. 
Fig. 20. Two cells at the margin of a fairly old prothallus, showing the megaspore membrane, 
x 650. 
Fig. 21. Two cells near the margin of the same prothallus as Fig. 26. x 650. 
Fig. 22. Prothallus cell with four nuclei, x 500. 
