80 Journal of the Mitchell Society [September 



lumen extending nearly the length of the cell, although the walls are 

 very much thickened. 



Chemical Composition of Cells in Garden Pea 



In very young flowers where the anthers were not open, light 

 green stains the walls nearly equal around the ovule. Ruthenin red 

 shows very little staining at any point. Methylene blue stains cell 

 contents, walls lightly if any. Cupro-ammonia destroys the walls en- 

 tirely in one hour. Chloroiodide of zinc stains brown color. This indi- 

 cates generally cellulose but not definitely. 



At the time of fertilization, all the cells except those of the micro- 

 pylar region remained the same. At the micropyle the light green 

 does not stain. Ruthenin red stains distinctly at micropyle. ]\Iethy- 

 lene blue stains cell walls deep blue, and destains in alcohol. In 

 cupro-ammonia micropyle cells are more resistant, remain intact after 

 two hours. This indicates presence of pectin appearing in micropyle 

 at time of fertilization. 



After fertilization the cell walls of the Malpighian cells modified 

 very rapidly in structure and took stains with difficulty. Chloroiodide 

 of zinc, one week after fertilization, stains brownish yellow except 

 at micropyle where it is l)lue. In half grown seeds it stains violet at 

 base and brown at outer part of cell. Iodine and phosphoric acid give 

 no distinct stain one week after fertilization. Iodine and sulphuric 

 acid on a mature seed gave a yellowish brown color at outer part of the 

 cells or the region of the cutin and blue in the inner half of the 

 cell, outer half unstained. Cupro-ammonia has little or no action on 

 cell walls. This indicates a cutin on the outside, inner part cellulose, 

 and outer part more impermeable. 



Mild hydrolysis was tried. Seeds of three ages were boiled slowly 

 for 20, 50 and SO minutes in .3 per cent HCl solution with reflux con- 

 denser. These were then tested with chloroiodide of zinc. Cell walls 

 all stained deep blue. Cupro-ammonia rapidly dissolved the walls. 

 On mature seeds iodine and siilplnirie acid gave a deep blue color 

 with much swelling, on young seeds gave a violet color. This dis- 

 tinctly indicates pure cellulose after treatment for 20 minutes in 

 weak IICl acid solution. Since this substance was so easily hydro- 

 lyzed it seems likely to have lieen a hemi-cellulose. Hemi-celluloses 

 are usually either some jiaragalactan or pento.se. Untreated seed 



