28 STKUCTUKE AND rilYSlOLOGY OF SEED PLANTS 



EXPERIMENT XII 



The permanganate test, to distinguish root from hypocotyl. Make a solu- 

 tion of potassium permanganate in water by adding about 4 parts, by 

 weight, of the crystallized permanganate to 100 parts of water. Drop into 

 the solution seedlings of all the kinds that have been so far studied, each 

 in its earliest stage of germination (that is, when the root, or hypocotyl, 

 has pushed out of the seed half an inch or less), and also at one or two sub- 

 sequent stages. After the seedlings have been in the solution from three to 

 five minutes, or as soon as the roots are considerably stained, pour off (and 

 save) the solution and rinse the plants with plenty of clear water. Sketch 

 one specimen of each kind, coloring the brown-stained part, which is root, 

 in some way so as to distinguish it from the unstained hypocotyl. Note 

 particularly how much difference there is in the amount of lengthening in 

 the several kinds of hypocotyl examined. Decide whether the peg of the 

 squash seedling is an outgrowth of the hypocotyl or of the root. 



EXPERIMENT XIII 



In what portions of the root does its increase in length take 

 place? * * Sprout some peas on moist blotting paper in a loosely 

 covered tumbler. When the roots are one and a half inches or 

 more long, mark them along the whole length with equidistant 

 dots made with a bristle dipped in waterproof India ink, or a 

 fine inked thread stretched on a little bow of whalebone or 

 brass wire. 



Fasten the peas with pins to moist blotting paper placed in a 

 vertical position under a bell glass or an inverted battery jar, and 

 examine the roots at the end of twenty-four hours to see along 

 what portions their length has increased ; continue observations 

 on them for several days. 



References. Detmer-Moor, 9 ; Pfeffer-Ewart, 31, II ; Darwin 

 and Acton, 11. 



17. Review sketches. Make out a comparison of the early life 

 histories of all the other seedlings studied, by arranging in par- 

 allel columns a series of drawings of each, like those of Principles, 

 Fig. 8, but in vertical series, the youngest of each at the top, thus : 



