SEED 125 



Cut thin sections with a dry razor from the endosperm of the 

 dry seed of Strychnos Nux-vomica : first mount a section in gly- 

 cerine, and observe, under a high power, the dense protoplasmic 

 body of each cell surrounded by a thick cellulose wall. 



Mount other sections in tincture of iodine not diluted with 

 water: then place a small drop of water at the edge of the 

 cover-slip, drawing it under by means of blotting-paper : observe 

 the edges of the section where the effect of the dilution will 

 first appear, and as the cell-walls swell, it will be seen that 

 they are traversed by fine threads of protoplasm, which are 

 stained by the reagent. 



Another method has been found to succeed well in demon- 

 strating continuity through the cell-walls of the endosperm of 

 various Palms, in which the endosperm has thick pitted walls 

 consisting of reserve cellulose : it is, to immerse the fresh sec- 

 tions in sulphuric acid in which a small quantity of powdered 

 Hoffmann's blue has been dissolved : when the sections are 

 sufficiently acted upon, wash them with water and mount 

 in glycerine. The protoplasm will be stained a deep blue, and 

 the swollen cell-wall is not stained : examine the swollen pit- 

 membranes, and if the treatment has been successful they may 

 be seen to be traversed by fine curved strands of stained 

 protoplasm. 



MATURE SEED AND EMBRYO. 

 (A) Dicotyledons. 



I. (a) Soak some Broad Beans for 24 hours in water : 

 selecting one which is fully swollen, note its flattened form, and 

 the dark blotch (the hilum) at one edge of it : this is the base 

 of the seed, by which it was attached to the parent plant. Dry 

 the surface of the seed and squeeze it gently, water will be seen 

 to exude from a small hole close to the hilum : this hole is the 

 micropyle, and is a guide to the position of the technical apex 

 of the seed, the whole being of the curved or campylotropous 

 type. 



Remove the tough outer seed-coat, derived from the integu- 

 ments, and the bulky, yellowish embryo, which occupies the 



