923 



foreign agency as inapplicable in determining the escape of the pol- 

 linia from their anthers, and to believe that impregnation in any 

 given flower is in this genus the result of the action of its own pol- 

 linia. The pollinia are erect, have no diaphanous margin, and de- 

 hisce along that margin which is internal with regard to the cell of 

 the anther, and which presents no appreciable difference of structure, 

 but corresponds with the margin of dehiscence of the pendulous pol- 

 linia first noticed by Mr. Brown. The base of the stigma is slightly 

 papillose in D. Rafflesiana, and more evidently so in the other spe- 

 cies ; and the fissures of communication are open in the former, but 

 closely approximated in the latter. In neither has Mr. Griffith seen 

 the pollinia engaged in these fissures, but they are either caught by 

 the processes of the corona or fall to the fundus of the corolla ; and 

 in whatever situation they emit their boyaux, the cord formed by the 

 aggregation of the latter always engages itself in the nearest fissure, 

 where it becomes more opaque and grumous. The cord then passes 

 upwards to the base of the stigma, along which it is reflected until it 

 reaches the union of the stigma with the styles, at which place it dips 

 into one of them, or rarely both, and proceeds downwards to the pla- 

 centa, causing a slight discoloration of the adjoining tissue. The 

 boyaux then separate, and proceed in every direction among the 

 ovula, to which they become firmly attached. They contain much 

 granular matter, which has a strong tendency to accumulate towards 

 their termination. Mr. Griffith states that he has observed an oscil- 

 latory motion, but no motion of ascent or descent, of the contained 

 granules. The tubes are simple, and one appears to be alloted to 

 each ovulum, to which it remains applied for some time, invariably 

 passing in at the centre of the fissure, and adhering so firmly that 

 they break across rather than separate. Mr, Griffith was unable to 

 demonstrate their termination internally by actual dissection, but in 

 one instance he observed the boyau to terminate about the fundus 

 of the fissure in a cul-de-sac, which was crowded with granules. 

 Whatever the function of these granules may be, similar bodies exist 

 in the cellular tissue of the ovula both before and after the applica- 

 tion of the tubes, and the majority certainly disappear before the 

 tubes reach the ovula. 



"No immediate change appears to be produced in the ovula by the 

 application of the tubes ; but some time afterwards the excavation 

 appears to enlarge and extend towards the point of insertion of the 

 tube ; and this action is continued until the whole of the granular 

 mass disappears, and the chief part of the ovulum is occupied by the 



