PLATE I. 



Fig. 12, 



Dry seed, opaque by j-in. objective. 



Shell of dry seed in turpentine ; a, substance of the 

 shell ; i, ridges of outer surface ; c, membrane 

 of outer surface; d, inner membrane, X 275. 



Section of dry seed shell X 250. 



Section of dry cotyledon X 55- 



Section of same in water X 250. 



Separated cells of seed ; a, of cotyledon ; B, of 

 radicle, X 275. 



Fragments of mustard flour X 250. 



Section of cotyledon cleared in potash X 500. 



Granules resembling starch, by i-io-in. H.I. ob- 

 jective. 



Section of soaked seed shell, the ridges swelled up 

 and membrane raised up from the pits of the 

 surface. 



Cells of outer membrane, in glycerine X 250. 



Piece of seed shell macerated in acid ; a, cells of 

 the husk ; i, ridges of the surface ; c, cells of 

 outer membrane, distended ; i/, cells of inner 

 membrane; e, true membrane of husk cells; 

 y, separated blocks of the shell. 



Appearance of shell and section; a, in water, by 

 \-\n. objective; i, by i in.; c, macerated in pot- 

 ash; d, in acid; e, in acid, by i-in. objective. 



To face page 25. 



