194 Mr. Griffith on the Oviilum q/'Santalurn, 



was inclined to consider that a reduction of parts similar to that which con- 

 stitutes in my opinion the second modification of Fiscum, occurred in Loran- 

 thus. But the obvious continuation of the tubes or sacs high up the stigmatic 

 canal seemed to present very obvious analogies with what is known of pollen 

 tubes. Besides this, the growth of the great bulk of cellular tissue, constituting 

 the first steps in the development of the embryo, could not be made to agree in 

 direction or situation with the similar growths in any modification of this sac 

 known to me. With the view of determining this point, I endeavoured in 

 many instances to trace the tubes upwards to the stigma, and, if possible, to 

 the pollen grains ; but 1 did not succeed in tracing them more than half-way 

 up the style, nor is this particular species well calculated to promise success 

 from the length of the style. 



Although I do not see any absolute theoretical objection to the attachment 

 of an ovulum to any part of the stigmatic canal, the inner surface of which 

 appears to me to have such direct relations with the placentae ; or to its being 

 reduced to a simple membranous sac ; yet the analogies were, I thought, in 

 favour of the derivation of these tubes from the pollen grains. And yet, con- 

 tradictory as it may seem, the arguments on which I founded this opinion 

 were of a negative character, with the exception of that which regards the 

 relation of an ovulum with the stigmatic canal, of which no instance was, I 

 believed, known ; for Osyris had rendered inapplicable a rule otherwise very 

 general, and so far as I previously knew, perhaps universal, that when an 

 embryonary sac exists, the embryo is developed within it. 



I also adverted to the fact of the tubes not appearing to exist before the 

 dehiscence of the anthers, and to their similarity in structure and appearance 

 to boyaux. But the first point, otherwise of minor importance, is much weak- 

 ened by Fiscum, as detailed by M. Decaisne ; and between that form of embryo- 

 sac, which is derived from the extension of a single cell, and pollen tubes 

 many things may be common. Both are membranous and extensible ; both 

 are generally the innermost membranes of their respective structure ; and the 

 contents of both appear to me to be much the same : and I need only allude 

 to Santalum to point out the great similarity that may exist between a pollen 

 tube and an embryo-sac. To these I added, that if they were embryo-sacs, 

 there are grounds for supposing that to each sac there would be an embryo. I 

 therefore inclined to the opinion, that in Loranthus there was nothing analogous 



