254 MR. MIERS ON THE STRUCTURE OF THE SEED 



raphe, is a development wholly unnoticed hy Dr. Gray, hy Endlicher, or by DeCandolle ; 

 hut it is an important feature, because it proves that the bony coating is the testa, and 

 not the tegmen as has been inferred. 4th. The raphe proceeding from the hilum is wholly 

 exterior to and free from the osseous coating, and interior to the outer tunic ; and this is 

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

 not in respect to testa and tegmen. 5th. 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 the product of the primine ; hence as the raphe is found in 

 a free state, though partially impressed in its soft substance, within the external tunic, 

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

 and in this manner enclosing the raphe. 6th. We have thus the evidence complete, of 

 the existence of the usual and distinct envelopes around the nucleus of the seed, viz. : — 

 an inner integument with its apical chalaza, an intermediate hard testa with its corre- 

 sponding diapyle, through which the nourishing vessels of the more exterior raphe pene- 

 trate, and the whole included within a scarlet-coloured soft arillus. 



From all these facts we may safely infer, that the envelope, which is unquestionably an 

 arillus in the Garciniece and the Tovomitece, must be of the same nature in the Clusieai, 

 and that which is arillus in the Clusiece must be the same development in the Magno- 

 liacea : that which is granted in the one cannot be denied in the other. Although it be 

 true that the several envelopes of the seed in different families are not to be recognized 

 alone by their consistency, which may be, contrary to general rule, more or less membra- 

 naceous, ligneous, cellular, or composed of oily or resinous granules according to circum- 

 stances, yet they may be determined by their relative position in regard to raphe, chalaza, 

 diapyle, micropyle, hilum, &c, from which their true nature may always be inferred with 

 greater certainty*. 



* The want of precaution in attending to the nature of the nourishing vessels proceeding from the placenta and 

 penetrating the different integuments, in order to promote the growth and perfection of the seed, has frequently led 

 to a misconception of its real structure. These vessels present themselves in the shape of a raphe-like cord under 

 three very different aspects : — 1st. When the cord, originating in the hase of the cell, terminates often at the opposite 

 extremity in the hilum of the contained seed; it is then properly the funicular cord, of which the common Cherry 

 affords a very good example : sometimes it is inappreciably short ; in other cases, as in Magnolia, it forms a very long 

 thread, by which the seed is suspended when it escapes from its cell. 2nd. When these vessels, existing in the form 

 of a thread, either free and exterior to the testa, or partially imbedded in its substance, spring from the point of attach- 

 ment of the hilum of the testa, and extending along its surface, penetrate its substance at a spot called the diapyle, to 

 unite with the chalaza of the inner integument, which is invariably opposite to the cotyledonary end of the embryo ; 

 this is the well-known raphe. 3rd. When the vessels passing from the hilum penetrate the inner integument and 

 extend in the shape of a thread beneath its surface, in order to attain the radicular (not the cotyledonary) extremity 

 of the embryo ; in this case they constitute the suspensor, which has sometimes been mistaken for a raphe ; it 

 occurs in Tropceolum, where its origin has been well illustrated and described by Dr. Giraud, in a memoir on the deve- 

 lopment of the embryo in that genus, published in the nineteenth volume of the Society's Transactions. The want of 

 attention to the existence and position of the true raphe has often led to erroneous inferences in regard to the affinities 

 of different genera, and among the Clusiacece may be cited the instance of Calophyllum. Gsertner (De Fruct. i. 200. 

 tab. 43. fig. 1) gives an analysis of its fruit, where overlooking the existence of the raphe, he has mistaken the extra- 



