232 GRIFFITH'S VIEWS [BOOK n. 



for the transmission of the latter to the primary utricle, and 

 through it to the embryo itself; for which office the structure 

 of its extremity (so like a spongiole) renders it peculiarly 

 fitted. 



" It may now," concludes Dr. Giraud, " be shown how far 

 the foregoing observations bear upon the undetermined 

 question of the origin of the embryo. That in this plant the 

 primary utricle and the future embryo never have any 

 structural connexion with the extremity of the pollen-tube at 

 their first origin, or at any subsequent period of their develop- 

 ment, is sufficiently obvious from the fact, that the pollen- 

 tube is never brought into contact with the embryo-sac. As 

 the primary utricle makes its appearance before impregnation 

 has occurred, it cannot be possible that that organ has ever 

 formed the extremity of the pollen-tube, as is believed to be 

 the case by Schleiden and Wydler. Moreover, as the primary 

 utricle takes its origin wholly within the embryo-sac, and at 

 the earliest period of its formation is not in contact with that 

 membrane, it cannot have been formed by the pollen-tube 

 pressing before it a fold of the embryo-sac in its passage into 

 the cavity of that structure, as Schleiden has maintained." 



Griffith is equally opposed to the opinion of Schleiden, as 

 to the action of the end of a pollen tube on the sac of the 

 embryo. His paper in the Transactions of the Linncean 

 Society, vol. xix., from which I make a few extracts, will well 

 repay the most careful perusal. 



" The first process in the development of the seed, subse- 

 quently to the penetration or application of the boyan to the 

 embryo-sac, would in Santalum, Osyris, Loranthus, and 

 Viscum, appear to consist of the formation of cellular tissue. 

 This may be applied, I believe, to most if not to all instances. 

 This cellular tissue appears to have two different origins; 

 one, and this is the earliest in development, being, perhaps, 

 referable to the embryo-sac, while the other appears directly 

 referable to the anterior ends of the pollen tubes. 



" In no instance, perhaps, where the embryo is developed 

 from the ends of the pollen tubes, does it become developed 

 so immediately that no cells intervene between it and the end 

 of the pollen tube ; this is particularly evident during the 



