Mr. Miers on the Structure of the Seed of the Clusiacese. 373 



external scarlet covering which preceding botanists call arillus, 

 while the hard crustaceous shell called testa even by Endlicher, is 

 there denominated tegmeri. This he infers from the fact of having 

 observed spiral vessels in the placentary attachment of the ovules, 

 which he thinks " clearly demonstrates that the baccate exterior 

 integument of the seed is formed of the primine of the ovule, and 

 therefore is not an arillus." Had the growth of this tunic been 

 actually traced from the primine of the ovule, an important fact 

 would have been established ; but simply because the primine is the 

 more exterior tunic of the ovule, and the arillus is the external coat- 

 ing of the seed, it does not necessarily follow that the one is the 

 product of the other, and notwithstanding the argument of Dr. Gray, 

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

 due to a subsequent growth over the primine, as occurs in numerous 

 well-known cases. Mr. Miers is confirmed in this view by observa- 

 tions which he made in Brazil upon living seeds of Talauma, a genus 

 closely allied to Magnolia : — First, he found the thick outer tunic to 

 consist of fleshy or oily matter, in distinct granules, enclosed within a 

 thin external epidermis, which is the usual texture of arillus, not of 

 testa. Second, the coating called tegmen by Dr. Gray, and considered 

 by him as the innermost integument, is in reality the intermediate en- 

 velope in Talauma : it has a small basal hilum, a longitudinal furrow 

 runs along its ventral face for the reception of the free raphe, and a 

 brown fungous scar through which the raphe finds a passage to the 

 interior, fills a distinct aperture near its apex (the diapyle), which 

 Dr. Gray, following the example of Endlicher, considers to be the 

 chalaza; this crustaceous envelope is thick and osseous in texture, 

 bearing all the characters of testa, certainly not of an innermost 

 integument of the seed. Third, the existence of an inner mem- 

 branaceous integument around the albumen, and within the true 

 testa, thickened and discoloured round its summit, where it is at- 

 tached by a short neck to the fungous process that fills the diapyle, 

 and where it unites with the raphe, is a development wholly unno- 

 ticed by Dr. Gray, by Endlicher, or by DeCandolle, although the 

 presence of this integument is indicated by Geertner ; but it is an 

 important feature, because it proves that the bony coating is the 

 testa, and not the tegmen, as has been inferred. Fourth, the raphe 

 proceeding from the hilum is wholly exterior to and free from the 

 bony coating, and interior to the outer tunic, and this is the constant 

 position of the raphe when it is free, in regard to arillus and testa, 

 assuredly not in respect to testa and tegmen. Fifth, as the raphe 

 consists of the nourishing vessels originally existing in the funiculus 

 or placentary attachment of the anatropal ovule, it could never have 

 existed between the primine and secundine, but must have been, as 

 Dr. Gray figures it, wholly exterior to the primine, and consequently, 

 as we afterwards find it, outside the testa, which is a product of the 

 primine ; hence as the raphe is found in a free state, though par- 

 tially impressed in its soft substance, within the external tunic, the 

 inference is irresistible, that the latter must be of posterior growth 

 (therefore of the nature of an arillus), and in this manner enclosing 



