Mr. Griffith on the Ambroslnla ciliata of Roxburgh. 275 



Tab. XL 



Fig. 7- Ovule at a very early period, and before hairs are developed from the surface of the 

 placenta : a. marks the site of the constriction ; b. papiUiform nucleus. 



Fig. 8. Ditto, more advanced. The nucleus projects considerably beyond the margins of 

 the cup formed by the enlargement of the annulus. The cellular hairs are now 

 developed; some even exceeding the ovulum in length. A fascicle of vascular 

 tissue is seen passing to the base of the ovulum. 



Fig. 9. Longitudinal section of the integument of a more advanced ovulum, leaving the 

 nucleus exposed. 



Fig. 10. Ovule more advanced ; the tegument is cut away as well as part of the short funicle 

 longitudinally. The nucleus is exposed, and seen to be entirely inclosed within 

 the tegument. It has undergone no alteration in form. Along its centre and 

 throughout its upper half, there is an evident excavation formed. 



Fig. 11. Longitudinal section of an ovule still more advanced. The irregular form of the 

 cavity of the testa and the dilated inferior portion of that of the nucleus are 

 distinctly visible. The embryo is still inclosed within the upper half of the 

 cavity. 



Fig. 12. Embryo, from about the same period ; it is now clavate, its conical apex has become 

 rather oblique, and on one side a depressed areola surrounded with a rather thick- 

 ened margin is visible. 



Fig. 13. Longitudinal section of the nucleus of a more advanced ovulum, a portion of the 

 base of the testa remaining. The apex of the nucleus is now perforated, and the 

 lower portion of the cavity is still more enlarged, and is seen to be occupied by 

 cellular membrane. The conical apex of the embryo is seen projecting beyond 

 the apex of the nucleus. 



Fig. 14. Nucleus, with portion of the base of the testa, still further advanced. The now 

 enlarged apex of the embryo is seen projecting beyond the nucleus, and the ori- 

 ginal conical apex has become more oblique. From the areola two teeth are seen 

 to project ; these are the rudiments of the outer processes of the plumula. The 

 apex of the inclosed portion has now reached to the dilated part of the cavity. 



Fig. 15. Embryo from the same placenta but from another ovule. The radicle is more 

 oblique, and the rudimentary processes, of which there are six, are more enlarged ; 

 none are developed from the centre of the areola. 



Fig. 16. A much more advanced ovule. The greater part of the testa is cut away; the 

 nucleus and enlarged apex of the embryo are exposed ; the radicle still preserves 

 its obliquely ascending direction, and there is still some degree of obliquity in the 

 plumula. 

 votf. XX. 2 o 



