170 Linnean Society. [April 18, 



" In Loranthus each ovulum appears to be reduced to an embryonary 

 sac, the albumen is developed either partly within the sac, or entirely, 

 or almost entirely, without it. The embryo is a growth from the 

 ends of the continuations of the pollen tubes outside the anterior 

 ends of the embryo-sacs, and is, in one modification, exemplified by 

 L. globosus, up to a certain period exterior even to the albumen. In 

 L. hicolor the albumen has no proper tegument ; in L. globosus it 

 may be supposed to have a partial one in the incorporated albumi- 

 nous part of the embryo-sac. 



" The gradation of structure appears to me to be tolerably complete. 

 One modification of Viscum, in my opinion, tends to show that in San- 

 talum the first steps towards the disappearance of the usual nucleus 

 take place. Osyris seems to me to indicate that a similar tendency 

 may affect the embryonary sac ; and Santalum appears to me to 

 allude to a reduction in the embryo-sac to the form of that of Osyris. 

 Nor is this all, Osyris has its albumen and embryo developed outside 

 that end of the sac to which the pollen tubes are applied : Loranthus 

 bicolor has the same developed outside the opposite end of the sac. 

 And the partial development of the albumen in the embryo-sac of 

 Loranthus globosus may perhaps be a passage to its development out- 

 side that sac in L, bicolor. 



" The novel points of structure and development pointed out in 

 this paper are, so far as I know, the possibility of the separation of 

 a continuous membranous embryo-sac into two distinct parts, of 

 which the lower remains unchanged, though it would almost appear 

 from Osyris to be the most permanent ; the presence of the embryo- 

 sac not being necessarily connected with its forming one of the con- 

 stituent parts of the young or of the mature seed ; the longitudinal 

 percursion of the embryo-sac by the pollen tubes ; the formation of 

 the albumen either only partially within the embryo-sac, or almost 

 entirely, if not quite so, without it ; the confluence of the albumina 

 of several sacs into one albumen ; the growth of the embryonic tis- 

 sues from the continuations of the poUen tubes outside the embryo- 

 sac ; the possibility of one embryo resulting from a combination of 

 several pollen tubes, and of its becoming interior to the albumen, 

 although it may have been for some time entirely exterior to it. 



" I make no mention of the posterior prolongations of the sacs, in 

 doubt of the true nature or origin of the so-called chalazal apparatus 

 of Thesium ; or of the growth of the embryonic tissues from the ends 

 of the pollen tubes, in doubt of my having misunderstood the obser- 

 vations of M. Schleiden, and in ignorance of those of M. Wydler." 

 In a subsequent note Mr. Cxriffith notices certain peculiarities in 



