394 Mr. GnirriTH on the Impregnation of Dischidia. 
demonstrate their terminations by actual dissection. In one case I have seen 
the boyaux terminate about the fundus of the groove or fissure in a cul de sac 
(Tas. XVIII. fig. 8), which was crowded with granules. They may frequently 
be traced, though indistinctly, towards the same point. 
Whatever the functions of the granules may be, similar bodies exist in the 
cellular tissue of the ovula both before and after the application of the tubes: 
they are probably much larger than the real fecundating agents, as Mr. Brown 
supposes. The majority certainly disappear before the tubes reach the ovula. 
With regard to the changes produced in the ovula after the application of 
the tubes, I may remark that there is no immediate effect produced. The 
cavity or nucleus I have already shown to pre-exist. Some time after the 
action of the tubes has commenced the excavation appears larger, and extends 
towards the point of insertion of the boyau. As this action is continued, the 
whole of the granular and globular mass disappears, and the chief part of the 
ovule is occupied by the now empty excavation (Tas. XVIII. fig. 7). No 
further appreciable changes other than in size take place for some time, and 
the rudiments of the coma are even visible before any part of the embryo 
appears to be formed. 
I shall conclude with observing, that the emission of the boyaux without 
the engagement of the pollinia within the fissures of communication, and 
without any appreciable cause to produce such an effect, is very remarkable: 
still more so is their passage to, and engagement in, these fissures. The 
passage of the cord upwards to the base of the stigma, and its subsequent 
reflection along its surface to the apex of the style is still more striking. 
What is the use of the papillosity of the stigma? One would imagine, that as 
the cord does not enter at this point, it might as well have passed directly 
towards the apex of the styles. It shows distinetly that this portion of the 
stigma exerts a peculiar and essential influence over the boyaux. 
The pre-existence of the nucleus or central excavation is contrary to what 
has been observed in Asclepias by Mr. Brown. There is the same correspond- 
ence between the attenuated extremity of this and the point of insertion of the 
boyau as in Asclepias. 
