84 MR. MIERS ON THE OUTER FLESHY COVERING OF THE SEED 



vessels of the raphe penetrating the outer coating at the hilum, that is to say, at the 

 extremity diametrically opposite to that of the original gangylode, and after running 

 alon"- its ianer siu'face, they find their way straight to the diapyle of the enclosed nut, 

 throuo-h which they pass to lose themselves in the chalaza of the inner integiiment, both 

 which points in the ripe seed (the diapyle and chalaza) correspond with the gangylode of 

 the ovule. 



I have endeavoured, by the accompanying figures, to render this question manifest. 

 Plate XIX. figs. 56 & 57 represent an ovule of Magnolia after Dr. A. Gray, showing the 

 broad placentary sheath which encloses the spiral vessels of the raphe. Fig. 58 is a longi- 

 tudinal section of the same, showing that the spiral vessels originate at the placenta and 

 hUum, and that they terminate at the opposite extremity, at the point of the gangylode, 

 which is the only point of the primine where these vessels traverse, in order to convey 

 nutrition to the secundine and nucleus : it is here evident that the sheath or extension 

 of the placenta containing these spiral vessels, must always remain exterior to the primine, 

 as weU as to the tunic resulting from its subsequent growth. Fig. 59 shows a section of 

 the ripe seed of Magnolia, where the placentary sheath (seen in fig. 58) during the incre- 

 ment of the ovule, has in the progress of its own growth, extended itself all over the 

 primine, and has become enlarged into an arUHform scarlet coating, and we have proof 

 that this coating is the result of such growth, by the fact that the raphe, retaining the 

 same position and direction, still remains enclosed in its substance. The primine, during 

 its increment, by the deposition of osseous cells within it, in the manner recorded by 

 Dr. Gray, becomes converted into the bony testa, shown in figs. 60 & 61, where the diapyle 

 or apertui'e is seen in its apex for the passage of the raphe, corresponding with the same 

 point of the gangylode in the ovule, through which these same vessels there penetrated : 

 we have evidence that this testa is the product of the primine, not only from this circum- 

 stance, but because it is exterior to another integument, the tegmen, which covers the 

 albumen, and which exhibits a chalaza in its apex, as seen in fig. 62. The above gives 

 us an example of the development of the simple raphe. 



As an instance of a branching raphe, I wiU select the seed of lAcania, shown in fig. 63 ; 

 this has a basal hUum, and is the growth of an anatropal ovule. Referring to figs. 56 & 58, 

 it is evident that the only point where the spii-al vessels can enter the primine, is at the 

 gangylode, the point which they passed thi-ough prior to the inversion of the ovule. If, 

 therefore, under the hypothesis of Dr. Gray, the raphe insinuated itseK into the 

 substance of the primine, it must, in the case of Licania, begin to send out its ramifi- 

 cations from the point at which it entered, that is to say, from the gangylode ; but on the 

 contrary, we find that all the vessels start from the opposite point of the hilum : the main 

 bundle directs a straight course (as in the case of the simple raphe) to the gangylode or 

 chalazal point, tin-owing out its redundant vessels in many lateral branches, while other 

 principal bundles start also from the hilar point, and spread themselves by continual sub- 

 division aU over the surface of the seed. Now it is clear, if these vessels were imbedded 

 simply within the primine, or in the tunic resulting fi'om its growth, that they must have 

 escaped from the placentary sheath and have pierced their way through the outer pellicle 

 of the primine, and insinuated themselves into its substance at a point near the micropyle. 



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