22 T. S. COBBOLD ON THE EMBRYOLOOY OF ACHIMENES I'ICTA. 



tube presented those familiar' appearances which (in other plants) 

 so long led Schleiden to believe that the apex of the sac was 

 actually inverted. Sometimes the appearances were very puzzling, 

 leaving it hard to say whether the pollen tube had been broken off 

 within the micropylar passage, or whether it had been entirely with- 

 drawn, leaving a cast or imj)ression by its previous contact with 

 the sac. In one particular instance the embryonal vesicle showed a 

 finely beaded filament attached below. The appearance thus pre- 

 sented was quite the reverse of that usually exhibited by a true sus- 

 pensor. In several ovules, as before remarked, there were indications 

 of the presence of two or more embryonal vesicles, the appearances 

 reminding me of what I had also frequently observed in Orchis 

 mascula. In this immediate connection I have likewise to add that 

 m one instance I noticed two pollen tubes projecting from one and 

 the same micropyle or exostome ; the same phenomenon having 

 also been witnessed by me in Orchis. As in this monocotyledon, so 

 in the dicotyledon Achimenes, bundles of pollen tubes may readily be 

 recognised within the ovarian cavity. They may be raised on the 

 end of a fine needle and drawn out for separate examination. Here 

 I may mention that in a different sort of plant, namely in 

 Grevillea phcenicia, I have observed a distinct folding in of the apex 

 of the embryo-sac. This appeared to have been brought about inde- 

 pendently, and without the presence of the pollen tube. The single 

 anatropal ovule in this genus is remarkably simple, showing all the 

 inclosed sac in a most attractive manner. 



As regards the further changes in the embryogenesis of 

 Achitiienes I have nothing to record, but in Orchis I have witnessed 

 the formation and growth of the embryo u]d to the stage of a small 

 globular parenchymatous bud. The yet further cell developments 

 within the embryo-sac of Orchis, which never proceed so far as to 

 result in the formation of a true endosperm, have not been observed 

 by me, but these must be very shglit, seeing that the ovular 

 coverings remain to form a loose reticulated perisperm surrounding 

 the exalbuminous seed. In Veronica gentianoides I have noticed 

 an undivided filament projecting from the microj)yle. These 

 projections, notwithstanding the absence of transverse septa, evi- 

 dently correspond with the confervoid filaments observed by 

 Schleiden in Orchis latifolia, and which he so strangely persisted in 

 regarding as pollen tubes. 



In reference to the subsequent changes undergone by the embryo, 



