14 Introduction to Botany. 



ments : Hold a lighted candle in the mouth of an inverted 

 bottle until the candle is extinguished. Cork the bottle, 

 set it right side up, and give the gas in it time to cool. 

 Then pour limewater into the bottle and shake vigorously. 

 The white precipitate will be produced as before. Blow 

 the breath through a straw or glass tube into another bot- 

 tle of limewater, holding the tube close to the bottom so 

 that the breath will bubble through the limewater. After 

 this process has continued for a short time the white pre- 

 cipitate of calcium carbonate will be observed. 



38. It would seem from these results that a chemical 

 process takes place in germinating seeds similar to that 

 which occurs in our breathing, or in the burning of a candle. 

 It will be interesting to note whether this process is asso- 

 ciated with visible changes in the reserve food supply in 

 the seed. Scrape a small portion from the reserve food of 

 a soaked grain of corn, and mount under a coverglass in a 

 drop of water; examine with a high power. Treat in a 

 like manner some of the remnant of reserve material still 

 remaining in the grain attached to a far-advanced seedling. 

 The starch grains in the latter preparation show erosions 

 like those shown in Fig. 3, page 21. 



39. To estimate the value of the reserve materials in 

 seeds to resumption of growth of the embryo, perform the 

 following experiments : Plant seeds of Lima bean in saw- 

 dust, chopped sphagnum, or other suitable seed bed, and 

 after the young plants appear, remove the cotyledons from 

 some of them, and leave others in their normal condition. 

 Compare the rate of growth of the two sets of seedlings. 

 Soak grains of corn in water over night, and remove the 

 outer food supply down to the fleshy cotyledon. Plant 

 both depleted and normal grains in moist s. ^nd note 

 their relative rates of growth. Try a similar ex t " ^^ f 



