106 DE. A. aBAY ON THE STRUCTUBE 



A short Exposition of the Structure i^f the Ovule and Seed-coats 



oi Magnolia. By Asa GtbM, M.D., T.M.L.S., &c. 



FEead Noyember 19th, 1857-] 



Ik 184i8, I maintained, in the ' Genera of North American Plants 

 Illustrated,' vol. i,, that the seeds of Magnolia were not aril* 

 late, but haccate^ or in other words, that the fleshy coat was the 

 testa. In 1855 this view was criticised by my excellent and most 

 ingenious friend Mr. Miers before the Linnean Society (see Ann. 

 and Mag. Nat. Hist, for May 1855) ; and he, upon speculative 

 groimds rather than from immediate observations, concluded that 

 " there is no reason to doubt that in Magnolia the scarlet envelope 

 is due to a subsequent growth over the primine," and is therefore 

 an arillus. As soon as Mr, Miers' remarks reached me, I re- 

 examined the ovules and young seeds of the plants in question ; 

 and the results of new observations by Mr. Sprague and myself 

 were publisbed in Hooker's ' Journal of Botany/ vol. vii. p. 243 

 (1855), and vol. viii. p. 26. The points which I supposed we had 

 settled by direct observation were : 



Ist, That no accessory covering, or arillus, was developed over 

 or upon the primine of the ovule ; but 



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2nd, That the fleshy envelope of the seed represents the primine 

 or outer coat of the ovule ; and 



3rd, That the bony coat of the seed was represented in the 

 ovule only by the innermost layer of young cells, lining the pri- 

 mine ; which cells, multiplying by merismatic division during the 

 growth of the seed, and their walls at length thickening and hard- 

 ening irregularly, form the crustaceous or bony coat ; so that the 

 character of the seed is best expressed by the term " driipaceous." 



Drs. Hooker and Thomson, about the same time (Flora Indica, 

 p, 73) also insist that the fleshy coat is the testa ; and notice the 

 delicate third coat, closely adherent to the albumen, but without 

 offering any opinion respecting the nature or origin of this and 

 the crustaceous coat*. 



Dtq. Hooker and Thomson remark, that " the lateral position of the raphe 

 with respect to the ovule and seed is worthy of note. It is well represented by 

 Mr. Sprague in the plates of Asa Gray's work just quoted, but is not noticed in 

 the text." If this refers to the pericarpic position of the raphes, that is only 

 mentioned in the description of the ovules, although there is no need of it, as 

 that position is the normal one {mde Gen. HI. p. 10) ; if it refer to the position 



description of the seed 



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er sides of the seed, that is also 



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