94 THE ORIGIN OF MONOCOTYLEDONS [CHAP. 



leaves being in any circle ; so that they may 

 arise at an angular distance of 120. Such is 

 the case in sedges and in the floral whorls ; but 

 the f , which supplies the quinary arrangements 

 of flowers in dicotyledons, cannot arise directly 

 from a single cotyledon. 



Of course the inference here suggested of 

 the single cotyledon, is that it is due to the 

 action of water in arresting the growth of the 

 second. The reader might ask if there are any 

 examples of dicotyledonous monocotyledons 

 now existing ; i.e. monocotyledons showing a 

 trace of a second cotyledon. Tamus communis 

 appears to have one (fig. 20, 1). One cotyledon 

 is described as forming a club-shaped absorbing 

 organ, which is embedded in the endosperm, the 

 other being a concave scale, while the epicotyl 

 forms a tuber, upon which the first two leaves 

 arise in a plane at right angles to that of the coty- 

 ledons. Asparagus (fig. 20, 2, 6) has also two, 

 one overlapping the other, the first pair of leaves 

 being at right angles to them, as in Tamus. 

 Certain grasses, as the oat, has a lobule opposite 

 the cotyledon, the plumule arising between them 

 (fig. 20, 4, 5). Certain monocotyledons develop 

 relatively large absorbing organs. I would 

 suggest that these also represent the cotyledon 

 which is usually suppressed. 1 



1 1 would refer the reader to Dutrochet's paper. c ' Observations 

 sur la Forme et la Structure primitives des Embryons Vegetaux," 

 Nouv. Ann. du Mus., vol. iv. 1835. Also to Grof zu Solms-Laubach's 



