448 BOTANICAL GAZETTE [December 



One of the rows of cells of the integument has become modified 



and now appears as a loosely scattered row of cells which connects 



the outermost layers of cells with the inner thickened hardened 



layer. Compressed cells, the remnants of the micropylar and the 



chalazal ends of the embryo sac at the time of fertilization, persist 



in the seed at each end just outside of the endosperm. The layers 



of cells covering the seed of various members of the Scrophulariaceae 



are described by Bachman. The number of layers of the testa of 



the seeds of the 128 species which he describes varies from one to 



four. 



Summary 



1 . The order of the development of the floral parts of Scrophu- 

 laria marylandica is calyx, stamens, corolla, and pistil. The stamens 

 and the corolla arise from a common outgrowth. 



2. The archesporium of the megaspore consists of a single hypo- 

 dermal cell, which functions as a megaspore mother cell. 



3. The megaspore mother cell by two successive divisions gives 

 rise to an axial row of four potential megaspores; the embryo sac 

 arises from the chalazal one, while the other three degenerate. 



4. The mature embryo sac contains one egg, two large synergids, 

 an endosperm nucleus, and three antipodal nuclei which soon 

 degenerate. 



5. A secondary endosperm nucleus, which grows larger as it 

 migrates toward the egg, was observed. A polar nucleus from the 

 chalazal end was seen to fuse with a polar nucleus from the 

 micropylar end. 



6. The first division of the fertilized egg is transverse, and is 

 followed by a longitudinal division of the chalazal nucleus, while 

 the other nucleus fails to divide until later. 



7. The nucellus consists of a single layer of cells which surrounds 

 the megaspore. 



8. A tapetal layer develops around the embryo sac. It is one 

 cell thick and begins to form at the time the megaspore mother cell 

 divides. At the chalazal end an extensive nutritive layer is formed 

 at the same time. 



9. Two well developed haustoria are formed at the chalazal 

 €nd of the embryo sac. Four less developed ones are formed at 

 the micropylar end of the embryo sac. 



