Reproductwe Organs of the Missel toe. 189 



plants, being accidental in the greater number, though always 

 constant in some. Ordinarily it occurs in seeds destitute of 

 perisperm ; but when this perispcrm is also present, the em- 

 bryos are pressed together at the same height, or at slightly 

 different heights. This, however, is not so in the Misseltoe ; 

 for the embryos, two, or more rarely three in number, all 

 touch each other by their lower extremities, and diverge at 

 their upper or radicular extremities, which are distant, and 

 separated by a jjortion of the perisperm, from which they 

 shghtly project. 



M. Decaisne's discovery of many ovula in the bottom of 

 each ovary leads to the most natural explanation of this 

 phjenomenon. In a great number of cases, two of these 

 ovula are abortive, and then a single embryo only is found 

 in the mature seed; but in other instances, two, or even three 

 ovula, being fertilized, are developed and united by their 

 bases, and then we have so many embryos diverging at their 

 summits. 



The results of this theory are, that it reduces the many 

 apparent anomalies of the Misseltoe to a single real one, the 

 unity of the ovular envelope, and thus restores the develop- 

 ment of its seeds to known laws. It also effaces in part the 

 difference between the ovular covering in the European Mis- 

 seltoe and that of the Indian species noticed by Mr. Griffith, 

 and in which three ovula are detected in each cell on a cen- 

 tral support. Our Misseltoe thus forms a transition between 

 them and Loranthus, in which the ovulum is really single and 

 erect. 



M. Decaisne has added to his memoir an examination of 

 the anatomical structure of the stem. A young branch ex- 

 hibits in its centre a green pith, surrounded by a case formed 

 of woody bundles, generally eight in number. In these 

 bundles we find no tracheae ; but nearly in the situation which 

 they should occupy, only annular vessels. These, together 

 with the elongated and pointed, or reticulated cellules, and 

 the fibres analogous to those of the liber, constitute the whole 

 vascular system of the plant, which is besides composed of 

 utricules, in which abound, together with granules of starch, 

 granules of green matter. Outside, and opposite to the 

 woody bundles, are as many smaller ones, formed exclusively 

 of fibres of liber, and which may therefore be termed cortical. 

 The woody bundles are continued from one branch into an- 

 other, whilst the cortical bundles are interrupted, after being 

 attenuated, at each joint, whence results the facility with 

 which the branches are disarticulated. 



