SECT. II. INTERNAL CHANGES. 3?3 



i 

 SECTION II. 



Internal Changes. 

 If the ovary is cut open as soon as it is first dis- Ovary di- 



. , visible into 



coverable m the flower, it presents to the eye merely distinct 

 a pulpy and homogeneous mass. But if it is al- or an * 

 lowed to remain till immediately before the period 

 of its impregnation, it will now be found to be di- 

 visible into several distinct parts, exhibiting an ap- 

 paratus of cells, valves, and membranes, constituting 

 the pericarp, and sometimes the external coats of 

 the seed. In this case the umbilical cord is also to 

 be distinguished ; but the embryo is not yet visible. 

 These changes therefore are to be attributed merely 

 to the operation of the ordinary laws of vegetable 

 developement, and are not at all dependant upon 

 impregnation. 



But impregnation has no sooner taken place than Umbilical 

 its influence begins to be visible ; the umbilical cord, cc 

 which was formerly short and distended, is now 

 generally converted into a long and slender thread. 

 Sometimes the position of the seed is altered. Before 

 impregnation the seeds of Caryophyllus aromaticus 

 and Metrosideros gummifera are horizontal ; after 

 impregnation they become vertical. Before im- 

 pregnation the seeds of Magnolia are erect ; after 

 impregnation they become inverted and pendulous,* 



* Gaert. De Seminibus. 



