981 



entirely distinct from the pollen-tube, and as forming an integral part 

 of the ovulum previous to fecundation ; all other parts being sup- 

 pressed in Loranthus and in some species of Viscum. As 1 have not 

 had the opportunity of examining any of the allied genera to which 

 he refers, I must confine myself to Viscum, concerning which ray 

 own observations lead me to doubt whether the embryo-sac, properly 

 so called, has any existence in the ovulum previous to fecundation. 

 The second modification of Viscum specified by Mr. GriflSth is that 

 of Viscum album, which, in his view, has the ovulum reduced to an 

 embryonary sac ; and if we consider it in connexion with the third 

 point (" the confluence of the albumina of several sacs into one albu- 

 men "), there arises a confusion of terms not very easy to be explain- 

 ed. Did Mr. Griflith suppose that in those cases where the seed 

 contained more than one embryo there were originally the same num- 

 ber of " embryo-sacs," combined into one ovule previous to fecunda- 

 tion ? or had he obtained a glimpse of those facts which I am about 

 to state, but which his multifarious pursuits prevented him from dis- 

 tinctly perceiving ? He appears to have attached much importance 

 to the existence of the embryo-sac in the ovulum previous to fecun- 

 dation ; for, in his concluding note of November, 1844, he states that 

 Osyris and Santalum have alike furnished evidence to prove "the 

 non-existence of any cell or body of or in the embryo- sac, from which 

 the embryo is derived, independent of the pollen-tube." His ap- 

 pended remark, that " the vesicle from which the embryo is to be de- 

 rived does not appear to exist before the application of the pollen- 

 tubes to the sac, it being in fact, so far as my means of observation 

 enable me to go, the anterior extremity of the pollen-tube itself," 

 tends to show that he had not obtained full demonstration on the 

 main point of the inquiry, and on this point I trust that my own re- 

 searches will now throw some further light. 



It is well known that the seed of Viscum album usually contains 

 two, and sometimes three embryos, and yet the ovulum consists of a 

 single cavity. I consider that this is very improperly termed an em- 

 bryo-sac ; for, as such, it presents the strange anomaly of being ex- 

 ternal to the albumen, and also of receiving within it a plurality of 

 embryos. At the very bottom of this cavity I find, some time after 

 fecundation (July 1, 1847), the three fusiform bodies represented at 

 fig. 8, their attenuated bases terminating in a single cellule, and not 

 more firmly fixed to the base of the ovule than is the seta of any spe- 

 cies of moss within the vaginula. In two instances I observed what 

 seemed to be portions of pollen-tubes, continuous with the apex ; 

 Vol. II. 6 g 



