394 Mr. Griffith on the Impregnation q/'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 

 (Tab. 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 (Tab. 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 poUinia 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 sul)sequent 

 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 distinctly 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 Asclepia.s 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 Asdepias. 



