ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 63 



pyle, long and very straight, is directed obliquely downwards and opens 

 over against the septum. The narrow transitory micellus is entirely 

 absorbed before the flower opens, to be replaced by a slender female 

 prothallus, having its summit at the bottom of the micropyle, and Lta 

 base near the end of the vascular bundle, from which it is separated by 

 a " hypostase " in the form of a thick cup composed of Ann-walled 

 lignified cells. The ovule, having no trace of a raphe, is neither ana- 

 tropous nor amphitropous, but belongs to the campylotropous group. 

 The fruit is a globose bilocular capsule, with four seeds, and a beaked 

 upper portion. This capsule opens from above downwards loculicidally, 

 and since the septum also splits, its dehiscence is also septifragal. The 

 seeds are set free by the formation of a ring of thick, lignified epidermal 

 cells at the rim of the large sunk hilum, which ring presses against the 

 septum, and effects separation. The cotyledons are incumbent, and 

 contain aleurone and oil, without starch. Nelsonia has approximately 

 the same structure, as also llendoncia, except that in the latter, the fruit 

 being a drupe, no separating ring is formed by the seed. These genera 

 the author unites into a group, which he provisionally calls the 

 Thunbergiea?. The ovary of species of Acanthus (mollis, longifolius, 

 spin os us) has a very thick septum, each half of which differentiates in 

 its interior two lamina?, perpendicular to the surface, formed of very 

 long, straight, thin-walled cells containing mucilage, but none of the 

 starch which abounds in the rest of the septum. This is certainly not 

 conducting tissue for the pollen-tubes, and its function is at present 

 doubtful ; in the capsule stage this tissue is seen to be lignified. The 

 two ovules of each cell are borne by a short, thick, oblkjuely ascending 

 funicle, and are flattened in a plane parallel to that of the septum. 

 Each receives avascular bundle from the septum, which bundle traverses 

 the funicle and ends at once in the ovule in the shape of a horse-shoe, 

 due to the phloem of the bundle reaching higher on each side than the 

 xylem. The integument of these ovules is very thick and wholly 

 cellular, and invests before the flower opens a straight nucellns, soon 

 replaced by a female prothallus of the same form. Here also there is a 

 " hypostase." The prothallus grows out and curves until it reaches the 

 bottom of the micropyle, and continuing its curvature thence it buries 

 itself in the integument on the opposite side of the ovule, in contact 

 with a rounded mass of small cells with thickened collenchymatous walls 

 and starchy contents destined to serve as nutritive tissue to the em- 

 bryo, since they gradually become dissociated and absorbed, much as 

 happens with the nutritive nodules produced by the placenta of the 

 Utricularias. These ovules are strictly campylotropous, as also are the 

 ovules, showing the same essential structure, of species of Whitjieldia, 

 Justicia, Ruettia, Aphelandra, and other genera. These genera are 

 ranged in a second group called Acantheas. The author regards the 

 retinaculum as simply a dorsal emergence from the funicle, and thus 

 comparable to a partial aril, differing from the normal aril in that it is 

 not detached with the seed. The rest of the memoir is of systematic 

 interest. Unfortunately there are no illustrations, an omission de- 

 tracting seriously from the value of the contribution. The author 

 suggests the division of the family into two distinct families, Thun- 

 bergiacea? and Acanthacea?. 



