Fig. 136. Sketches to illustrate the theory of the origin of monocotyledony from 

 dicotyledony by transfonnation of one cotyledon into a suctorial organ. A to F, 

 germinating seeds and seedlings of Pepsromia spp. and G to /, a monocotyledon 

 showing stages in the evolution of a monocotylcdonous embryo from a dicoty- 

 ledonous embryo. A, B, Peperomia pellucida, two cotyledons withdrawn from the 

 seed coats; C, D, P. peruviana, one cotyledon withdrawn, becoming an assimilating 

 organ, the other remaining in the seed and becoming an absorbent organ; E, F, P. 

 parvifolia, one cotyledon an assimilating organ, the other a club-shaped, absorbent 

 organ in the seed; G, H, I, a monocotyledon: G, in germinating seed, one cotyledon 

 an absorbing organ, the other a rudimentary first leaf; H, the embryo, except for 

 the absorbent cotyledon, withdrawn from seed coats; I, the larger cotyledon re- 

 maining in the seed as a scutellum, the other forming a small leaf, c, cotyledon; 

 c', c", absorbing and assimilating cotyledons, respectively; e, endosperm; h, hypo- 

 cotyl; p, plumule; pm, perisperm; pt, pericarp and testa; r, root; t, testa. (After 

 Hill.) 



361 



