10 MR. HENFREY ON THE DEVELOPMENT OF THE OVULE IN ORCHIS MORIO. 



Lastly, although the production of the confervoid filaments appears to be a normal pro- 

 cess, it is still a question open to doubt when only observed in ovaries containing such an 

 abundance of ovules as Orchis Morio. 



The facts I have detailed above are, however, agreeable with what I have observed in 

 certain other plants, in some as yet imperfect investigations ; I hope to be able to complete 

 them, and to repeat the earlier examinations with especial reference to the doubtful points, 

 in the course of the ensuing summer. 



EXPLANATION OP THE PLATE. 

 Tab. II. 



(The Figures are all magnified about 200 times.) 



Orchis pyramidalis. 

 Fig. 1. A young ovule. 



Fig. 2. The same, somewhat more advanced. The ovule presents a single coat, enclosing the nucleus, 

 which consists of a layer of cells (the coat of the nucleus), surrounding a large central cell (the 

 embryo-sac). 



Fig. 3. An end view of the summit of the last. 



Orchis Morio. 



Fig. 4. A young, almost erect, ovule with a single coat, from which the nucleus projects. 



Fig. 5. A more advanced ovule, curving round and exhibiting the nucleus and embryo-sac more 



distinctly. 

 Fig. 6. More advanced stage, ovule almost anatropous; both coats are now distinguishable, the inner 



projecting out from the outer, and the nucleus beyond the inner. 

 Fig. 7- The inner coat has grown over the nucleus, which still retains its proper cellular coat (7 a). 

 Fig. 8. The outer coat has grown up further; the nucleus has lost its coat, and is now a simple sac filled 



with a clear fluid in which float black granules (8 a). 

 Fig. 9. The outer coat almost completely covers the inner, which, with the nucleus, is indicated by 



dotted lines. The endostome is now very narrow ; the nucleus contains mucilaginous matter 



(protoplasm, 9 a). 

 Fig. 10 to 14. Embryo-sacs from ovules a little more advanced than in fig. 9, exhibiting the vesicles at 



the micropyle end. 

 Fig. 15. An ovule with the pollen- tube penetrating. The exostome is a wide mouth, the endostome very 



narrow. The blind extremity of the pollen-tube lies upon the outside of the embryo-sac, within 



which is seen one large germinal vesicle. 

 Fig. 16 to 22. Embryo-sacs with pollen-tubes in contact, and with germinal vesicles within. In 

 Fig. 20 & 21 the germinal vesicle has divided into two cells by the formation of a transverse septum. 

 Fig. 23 to 29. Different stages of development of the confervoid filament from the pro-embryo. In 



fig. 25 the pollen-tube lies beside it. In fig. 29 the upper cells of the filament exhibit the con- 

 - tracted mucilaginous layers (primordial utricles) detached from the cell-walls. The lower part, 



which produces the embryo, is filled with opake mucilage, which appears to divide into 



separate cells in various ways. 



