982 



but this is a point which I am compelled to leave for future inquiry, 

 having commenced my examination this year and in 1845 too late in 

 the season. It seems highly probable that the pollen-tubes penetrate 

 to the bottom of the ovule, and that their extremities become trans- 

 formed into these fusiform bodies, and if so, it follows that neither 

 the albumen nor the embryo-sac, properly so called, has any exis- 

 tence in the ovule until fecundation has been effected. I consider 

 these fusiform bodies lo be each a rudimentary mass of albumen, con- 

 taining near its apex the true embryo-sac, with its included embryo- 

 nary vesicle, as is evidently shown by their appearance at a subse- 

 quent stage (August 23). They are at this period enlarged, as 

 represented at fig. lie, and not unfrequently one of the three is abor- 

 tive. Such as ai'e fertile now coalesce to form one body of albumen, 

 which as yet only partially fills the cavity of the enlarged ovule, and 

 the embryos (fig. 11^) are still only half developed, with faint traces 

 of cotyledons. At this period the viscous sarcocarp of the seed may 

 be seen radiating in numerous faintly spiral threads, issuing from the 

 surface of the veiny innermost integument of the future seed. 



The introduction of pollen-tubes is a fact of too much importance 

 to be admitted on any but the most incontrovertible evidence; though 

 it will materially tend to remove doubt if the tubes can be traced, in 

 this plant, even into the style ; for the tissue of the stigma is more 

 dense than that of the style, and lower down the cellules are so loose 

 as to present no barrier to the progress of the tubes to the very base 

 of the ovule (a distance of less than the twelfth part of an inch) ; but 

 as yet I have not witnessed any penetration whatever below the sur- 

 face of the stigma. It will be interesting to ascertain why the num- 

 ber of pollen-tubes admitted into each ovule is restricted to three. 

 The union of two or more embryos in one seed seems to be a provi- 

 sion to secure the propagation of a plant, which being dioecious might 

 otherwise become extinct. The fusiform bodies are evidently not 

 separate ovules; for their attenuated bases have no resemblance in 

 structure to funiculi, and have no vascular tissue ; indeed, their con- 

 nexion with any supposed placenta, except by mere contact of a cel- 

 lule, is altogether problematical. 



In Viscum album the ovule appears to be naked, as in Juniperus, 

 and to consist of only one distinct membrane (the embryo-sac of Grif- 

 fith), which afterwards becomes the veiny inner coat of the seed ; but 

 if the sarcocarp exists ah initio, it may be regarded as the primine, 

 the veiny integument as the secundine, and the loose cellular tissue 

 within it (which also serves the purpose of conducting stigmatic tissue, 



