280 Mr. J. Miers on the N^ature and Origin 



Against this combined authority I demurred, by showing* 

 that the cord of the raphe being found within the scarlet coat- 

 ing, it was absohitely impossible, if that tunic owed its origin 

 to a mere growth of the primine, that the raphe could have 

 quitted its normal position outside the priminef, and have sub- 

 sequently insinuated itself into its tissues. 



Dr. A. Grav, in his last paper J, again repeats that the scarlet 

 coating and bony nut are both derived from a growth of the 

 primine, as he witnessed upon the inner surface of the latter the 

 gradual deposition of osseous cells, subsequently forming the 

 hard shell. There can be no doubt of the fact of this depo- 

 sition, but I dissent from the inference just mentioned. If what 

 my excellent opponent designates a "baccate testa" be one tunic 

 resulting from the mere growth of the primine, we ought to find 

 it consisting of three parts, as stated in my second preceding- 

 definition ; but, on examination, we find double the number, or 

 two distinct tunics, the outer having its endoderm and epiderra, 

 which in the ripe seed I found a black and softer surface, easily 

 scraped ofi', and showing the nut beneath of its usual pale yel- 

 lowish colour. I will not enter into the question whether the 

 previous growth of the primine is due to •''merismatic division," 

 as supported by Dr. Gray, or whether it is due to other sources, 

 after the theories of dilfereut physiologists. B)it when it has 

 attained to nearly its full growth, the mode of the solidification 

 of this tunic is probably effected by means of the intercellular 

 passages, so clearly indicated by Link, as existing between the 

 cells of fleshy tissue ; osseous matter, secreted probably from 

 the nourishing vessels, would here readily flow into those spaces 

 and become absorbed into or deposited round the cells of that 

 tissue. By these means the whole iiiterual mesodermal mass 

 would become solidified into a compact hard shell, and the pre- 

 viously harder epidermal surface of the primine would now be 

 comparatively the softer, and be readily scraped off" the nut, as I 

 found it in l^ahiuma. This view corresponds with the structure 

 observed in the ripe fruit ; while, on the other hand, under the 

 supposition of Dr. Gray, that the two outer seed-coats had pre- 

 viouslv existed under the form of one sinsle homogeneous tunic. 



coloratura, testa subossea." Lindley (Veg. Kingd. 417), speaking of Mar/- 

 noliacece, and referring to the tribe Magnoliea as distinct from lUiciece, re- 

 marks, " seeds often covered by an aril." The only botanist who speaks 

 ambiguously on the subject is St. Hilaire, who s?ys generally, that where 

 the seed-coats ai-e of different natures and confluent together, he will, for 

 the sake of convenience, consider them as one. 



* Linn. Trans, xxii. d-Q. j See the preceding second definition. 



t Journ. Linn. Proc. ii. lOfi. 



