liEHMINATION. 



123 



614. The germination of monocotyledons, as seen in Indian corn, 

 wheat, tulip, is in this wise. The cotyledon is not disengaged from the 

 seed, but remains stationary with 



it. The radicle (r) protrudes 4S3 4S4 



slightly and one or more rootlets 

 (s) break out from it and descend. 

 The plumule (c) shoots, at first 

 parallel with the cotyledon along 

 the face of the seed, but soon as- 

 cends, pushing out leaf from with- 

 in leaf. 



615. The conditions requisite 

 for germination are moisture, air, 

 and warmth. 



6} 6. Moisture is necessary for 

 softening the integuments, dis- 

 solving the nutritive matter, and 

 facilitating its circulation. This is 

 supplied in the rain and dew. 



617. Air, or rather its oxygen, 

 is required for the conversion of 

 the starch into sugar — a process 

 always depending upon oxydation. 



The oxygen absorbed unites with a portion of the carbon of the starch, 

 producing heat, evolving carbonic acid, and thus converting the re- 

 mainder into grape sugar, soluble and nutritive. 



618. Warmth is a requisite condition of all vital action, as well in 

 the sprouting of a seed as in the hatching of an egg. The proper de- 

 gree of temperature for our own climate may be stated at 60°" to 80°. 

 Extremes of heat and of cold are not, however, fatal to all germination. 

 In one of the Geysers of Iceland, which was hot enough to boil an egg 

 in four minutes, a species of Chara was found in a growing and fruitful 

 state. A hot spring in the island of Luzon, which raises the thermo- 

 meter to 187°, has plants growing in it and on its borders. Many 

 species of plants also seem well adapted to growth in the Arctic 

 regions. 



619. Darkxess is favorable to germination, as proved by experiment, but not 

 an indispensable condition. Hence, while the seed should be covered for tho saka 

 of the moisture and shade, the covering should ba very thin and light, for the sake 

 of a free access to air. 



4S4, Germination of Indian Corn. 



