of the Vegetable Ovule. 



19 



Fit 



a very philosophical spirit, in his investigation into the growth 

 of the ovule of Magnolia* from its earliest periods; he confines 

 himself solely to the appearances seen in the different stages of 

 its growth, which he illustrates by figures, without reference to 

 any theory on the subject : those figures well accord with the 

 explanation I have rendered of Mirbel's illustrations of the de- 

 velopment of the ovule in Aristolochia and Tulipa; but there 

 appears to me some little error in fig. 2, where the earliest pul- 

 lulation is always somewhat excentric in instances of anatropy — 

 never at the extreme tip, which would generate an atropal ovule. 

 I need not here recite the details of my own observations 

 made in the spring of last year, upon the mode 

 of growth of the anatropal ovule of Amygdalus\ ; 

 suffice it to say that I have repeated them this 

 year with the utmost care, from the very ear- 

 liest periods of growth, and all that I had pre- 

 viously remarked is fully confirmed. I have no- 

 ticed here, in every instance examined, as shown 

 in the marginal figures, a deep depression 

 completely upon one side (never at the extremity) 

 of the wart-like pullulation from the placenta, 

 which I have called the placentary sheath, because 

 it encloses in its parenchyma the tracheal vessels V-^sptx 

 of the future raphe, in the bottom of which j 

 hollow there is a small budding-point where the 

 vessels terminate ; and out of this point the nu- 

 cleus originates, standing in the bottom of the 

 hollow : this nucleus soon becomes surrounded 

 by the annular rudiment of the secundine, while 

 the margin of the depression by degrees expands 

 into a cup of a horse-shoe form, the two arms 

 of which abut upon and embrace a lamellar plate 

 of the placenta, and the opposite extremity is 

 rounded into a concentric form, surrounding and 

 including the nucleus and secundine. In Prunus 

 the wart-like protuberance is more globular than 

 in Amygdalus ; and upon one side, not far from 

 the placenta to which it is attached, there is a 

 very deep circular depression, in the bottom of 

 which the diminutive nucleus is seen rising from 

 the budding-point : this is gradually encircled 

 by the secundine ; and the deeply hollow support 

 becomes first a cup, which finally grows down- 



* " A short exposition of the structure of the ovule 

 and seed of Magnolia" Journ. Linu. Soc. ii. 106. 



f Ann. Nat. Hist. 3 ser. i. 359. 



9* 



