192 Mr. Griffith on the Ovulum of Santalum, 



engagement of the pollen tube between the cellular teeth of the apex of the 

 sac ; on the constantly associated presence of the vesicle with tubes adhering 

 to the apex of the sac * ; on the occasional indications of a direct passage 

 between these ; and on the changes the vesicle subsequently undergoes. 



The appearance of this vesicle is almost always that of a rounded cell 

 containing molecular matter, at first very mobile : very frequently a neck is 

 obvious, which, however it may appear at first sight, always corresponds in 

 direction with the opake line in the centre of the apex of the sac, and which 

 is in my opinion the line of passage followed by the boyaux. The margins of 

 this vesicle are almost always such as a simple sac would present ; occasion- 

 ally it has appeared to be lobed, and occasionally I have seen indications of 

 another vesicle. Such appearances as these last I would endeavour to explain 

 by supposing the penetration of two or even more boyaux, the application of 

 more than one not being very uncommon. 



The occasional appearances of inflection are such as would arise from the 

 relations of a vesicle that has penetrated a grumous, often, as it appears, a 

 bilobed mass, to that mass ; and it was to explain those appearances, which 

 are common, that I paid particular attention to the intimate structure of the 

 apex of the sac before fecundation. And I beg distinctly to state that I have 

 seen no appearances that would lead me to consider that the sac itself suffered 

 any considerable or constant inflection before the boyaux. 



The vesicle has appeared to me generally to remain unchanged until the 

 nucleary aggregation of the molecular matter of the sac has reached to some 

 extent ; its free margin I have then found to present traces of internal divi- 

 sion, first pointed out by nucleary aggregation, then by the shadowing out of 

 as many cells as there are nuclei ; the further changes it undergoes will be 

 subsequently noticed. 



In Osyris I was not able to detect any inflection or penetration of the sac 

 of the embryo by the boyau. This seemed merely to expand upon the sac, 

 occasionally causing indentations on its surface : indeed it appears to me that 

 penetration would in this instance present an unexampled anomaly. 



* To this I have only met with one exception, although I have examined some hundreds of sacs. 

 Yet it would seem obvious that the hoyau might be as liable to break off within the teeth of the apex of 

 the sac as without. 



