16 DR. J. D. HOOKER ON THE STRUCTURE AND 



tuose in some species of Balanophora : in all the Helosidece they burst introrsely, and 

 also l\v their apices, which decay away, and thus allow the pollen to escape. 



The tissues of the anthers present little peculiarity ; that of the connective is simply 

 cellular, without any of the spu'al vessels or beautiful modifications of banded or annulate 

 cells, so conspicuous in the endothecium of many plants. It is frequently lined with a 

 pulpy mass of mucilaginous filaments of excessive tenuity, which appears to be the 

 remains of the tissue amongst which the pollen-cells M'ere elaborated. 



The pollen of various species has been carefully described by Gceppert, Griffith, and 

 others, and presents nothing remarkable : it is generally spherical, often 3-lobed or 3- 

 nucleate ; in Ilijslropetalon it is polygonal. The surface of the extine is occasionally 

 minutely granulated. Impregnation is probably mainly effected by insect agency, and at 

 night ; for during the day there is a singular want of insect life in the still, humid forests 

 frequented by the species of Balanophora. I have, however, failed in many attempts to 

 trace insect action ; and a small Acarus feeding on the pollen of the monoecious B. invo- 

 lucrata is the only one I have found to be concerned in the operation, and that no doubt 

 quite accidentally. The necessity of cross impregnation is manifest in the Selosidew, as 

 indicated by Richard, and elsewhere explained in this Essay (under the genus). The fact 

 of insects forming a nidus in the fleshy plants of this Order, has been used as an argument 

 in favom- of insect action assisting in impregnation ; but the same might be apjilied to 

 any fleshy fungus or fruit. 



Ovaries. — These vary in number, from one in the Moiiosfijli and Sarcophyte, to two in 

 the Dlstyli ; and, according to Endlicher, to sometimes three in Selosis and Scyballwm. 

 "When there are more than one, they are congenitally coherent, enclosed Avithin the ad- 

 herent perianth, and all the cavities but one are suppressed (being rarely present, according 

 to Endlicher and Schott, in some floM'ers of Selosis and Scybalium), whilst the styles 

 invaria1)ly remain, and are equal, and symmetrically disposed (right and left to the axis) 

 at the summit of the perfectly symmetrical one-celled ovary. In those species which 

 have a perianth, it may be traced surrounding the ovary, if examined before the latter 

 begins to swell, and at all periods in some species ; in most, however, the walls of the 

 ovary become indurated, and blend insensibly with the adherent perianth, whose limb 

 however generally remains, as the two-lipped calyx of the Bistyli : in the LoplwpliytecB it 

 is truncate and suppressed ; and in Cynomorium, Mystropetalon, and Sarcophyte, its struc- 

 ture has been abeady explained. Amongst the Monostyli the ovary is always one-celled ; 

 and in Laiujsdorffia and Thonningia it is enclosed in a very evident perianth. In Bala- 

 nophora there are not even rucUmeutary traces of a perianth. 



The style varies considerably in the Order. In Balanophora, Langsdorffia, and Thon- 

 iiingia, it is reduced to its simplest form, namely a cellular column composed of a very 

 few oblong cells sm-rounding a soft, pulpy, stigmatic tissue ; the latter does not form a 

 distinct stigma, and the termination of the style scarcely differs from any other part of 

 that organ. The pollen appears to take effect anywhere towards the apex of the style, and 

 I have found pollen-tubes in the axis of the style. In the Bistyli the style is usually 

 capitate, and rather more perfect than in the Monostyli, terminating in a few larger, often 

 globular cells. After impregnation, the walls of these cells, when very highly magnified, 



