44 Elementary Plant Physiology. 



in seeds in a vertical position. Note the manner in which the 

 cotyledons are withdrawn from the testa, and also the action 

 of the hypocotyl, due to its unequal growth. Ascertain the rate 

 of growth. What is the fate of the cotyledons? Compare 

 with Ricinus and the pea. Make exact drawings of the earlier 

 leaves, and compare with adult forms. Follow the course of 

 growth of the roots, and note the origin of the branches and 

 root-hairs. 



39. Germination and propagation of Begonia. 

 Trail a stem and leaves of any species of Begonia of which 

 fresh seeds are at hand, across a shallow box containing moist 

 soil or sand. Lay small stones on the leaves and stems to 

 press them firmly on the soil. As soon as roots are formed, or 

 buds are developed, cut the stem and the leaves into convenient 

 portions, each of which is furnished with a root or bud, and 

 imbed in a separate dish of sand or soil. Follow the growth of 

 the plantlets from these cuttings. Are the plantlets grown from 

 the stem similar to those originating from the leaves or not? 

 Compare with seedlings which have been grown at the same 

 time. Which series develops most rapidly? Are any differ- 

 ences to be noted between the plants arising from the cuttings 

 and from the seeds? 



40. Germination of seeds of Peltandra Virginica. 

 Collect seeds of Peltandra, which may be found floating 

 around the margins of ponds in early spring, and place in a 

 vessel containing spring water, and keep in a room at ordinary 

 temperatures. Examine the thin pericarp, the integuments, 

 and the embryo in the seed. Note the occurrence of two impor- 

 tant events in the germination. The first leaf begins to en- 

 large, and frees itself from the clasping cotyledon, and the outer 

 integument of the seed begins to swell, finally attaining a 

 bulk greater than that of the seed in its resting form, break- 

 ing up the pericarp, which is freed and lost. Follow the 

 development of the roots. Note the position in which the 



