of the Vegetable Ovule. 15 



anatropal ovule of Aristolochia, fig. 1 is a simple pullulation from 

 the placenta, the rudiment of the primine, or what I have called 

 the placentary sheath, because it encloses in its tissues the nou- 

 rishing vessels that terminate in a certain budding point, and 

 that form the future raphe ; it is not the nucleus, as is generally- 

 taught. Close to the extremity of this, out of a circular depres- 

 sion, the first appearance of the nucleus is exhibited in fig. 2. 

 The secundine next presents itself in the same hollow, surround- 

 ing the base of the nucleus in fig. 3. After this we observe the 

 gradual swelling of the under part of the nuclear support, or the 

 downward growth of the placentary sheath, which becomes the 

 primine, in the form of a bag suspended by the remaining sti- 

 pitate portion of the sheath or funicle, — the original margin of 

 the depression first described remaining as the mouth of this 

 bag, and constituting the foramen of the primine (micropyle or 

 exostome), which from first to last never changes its position or 

 its aspect — a most important point to be observed. During this 

 action of centrifugal growth, the chalaza, or place of attachment 

 of the nucleus, necessarily recedes from its original position, 

 remaining at the bottom of the growing bag or primine, the 

 extension of the nourishing vessels keeping pace with its down- 

 ward growth, and still terminating in the now basal chalaza ; at 

 the same time, the enclosed nucleus and secundine severally 

 grow upwards, both constantly attached to the budding or cha- 

 lazal point of their origin : all this is seen in fig. 5, which repre- 

 sents a perfect ovule ready to receive the poUinic influence. We 

 find in fig. 6 exactly the same disposition of the parts after the 

 ovule has been impregnated, and when the embryo-sac with the 

 nascent embryo has been developed. In these several stages 

 we perceive that the foramen of the primine, the mouth of the 

 secundine, and the apex of the nucleus, from first to last, all 

 culminate towards one common point, while the basal portions 

 of the same parts as constantly point downwards : if the expres- 

 sion may be allowed, they all retain the same uniform polarity ; 

 there is no inversion in any of the parts, or even an approach to 

 it j the hilar or funicular point of attachment is not transported 

 from the base of the ovule to its superior extremity, as asserted ; 

 and there is no agglutination {soudure) of the primine to the cord 

 of the raphe, elongated by this assumed act of semirevolution 

 of the ovule.* In fine, although the mode of growth, as shown 

 in the drawings, is perfectly correct, there is throughout the 

 whole description a misconception, and a complete mistake in 

 the use of all the terms employed by Mirbel, especially in those 

 I have denoted by italics. The same mode of growth is again 

 still more fully demonstrated in plate 7, in the instance of Tu- 

 lipa. Nowhere among the other numerous exemplifications in 



