Dr. Gjrauds Contributions to Vegetabk Embryology. 169 



necessarily arise from that axis. Hence the opinion held l>y many morpho- 

 logical writers, that the axis results from a union of the cotyledons, or of 

 their petioles, is proved to be without foundation , for the foregoing otoca va 

 tions show that the lateral projections, which constitute the first traces of the 

 cotyledons, are composed of cellular tissue developed at these points of the 

 axis, and are therefore new formations arising from determinate points, and 

 deriving- their nourishment from the substance of the axis. 



EXPLANATION OF TAB. XVI. 



Pig. 1. Section of a carpel of Tropaolummajus, before impregnation, a. Raphe, b. Apex 

 of the nucleus and exostome. c. Columella, d. Prolongation of the carpcllary leaf 

 contributing to the formation of the style, e. Closed extremities of spiral vessel 

 and annular ducts. 



2. Section made at a more advanced period, a, b, e. As in fig. 1. /. Embryo-sac 

 ff. Canal leading from the apex of the nucleus to the embryo-sac. h. Organisable 

 mucilage with cytoblasts. 



S. Section just before impregnation, a, b, e. As in fig. 1. f.g. As in fig. 2. h. Pri- 

 mary utricle filled with cytoblasts. 



4. Section immediately after impregnation, a, b, e,f. h. As in fig. 3. ft. Spherical body. 



forming the first trace of the embryo at the extremity of the primary utricle, i. Pc- 

 villa, with its granules, in the canal leading from the style to the micropyle. 



5. Section, showing the embryo distinctly formed, a, e,f. As in fig. 4. h. Primary 



utricle, now become the suspensor or umbilical cord. k. Embryo. /. Cells con- 

 nected with the suspensor. m. Cellular process proceeding from the suspensor 

 into the carpellary cavity. 



6. Embryo, suspensor and its cellular process removed from the ovule, h. Suspensor. 



k. Embryo. /. Cells connected with the suspensor. m. Cellular process of the 

 suspensor. 



7- Section, after the appearance of the first traces of the cotyledons, h. Suspensor. 

 k. Embryo, with the first appearances of the cotyledons. /. Cells connected with 

 the suspensor. m. Cellular process of the suspensor. 

 VOL. XIX. z 



