THE EMBRYO 207 



onous forms there may be early abortion, which may even 

 approach suppression, of one of the cotyledons ; and that ^n 

 consequence of this the single functional cotyledon may appear 

 terminal and the stem-tip lateral. To call such cases " pseudo- 

 monocotyledons/' however, is not consistent with the real nature 

 of the monocotyledonous embryo. It is of interest to note, how- 

 ever, that Miss Sargant, 94 in her recent study of the "' mono- 

 cotyledonous Dicotyledons," a special case being made of Ranun- 

 culus Ficaria, has concluded that the apparently single cotyle- 

 don is a fusion of two. 



The peculiar development of the cotyledons of Nelumbo has 

 suggested to Lyon 74 ' 75 that they represent a single two-lobed 

 cotyledon, and that this fact, along with certain anatomical 

 details, should place Nelumbo among the Monocotyledons. In 

 its early stage he represents the proembryo as being a many- 

 celled spherical body, that later becomes a flattened mass filling 

 the micropylar extremity of the sac. The stem-tip arises from 

 the free surface toward one side, and a cotyledonary ridge 

 arises behind it as a crescentic mound of tissue, whose wings 

 finally extending around form a sheath about the stem-tip. 

 By the development of two growing points on this cotyled- 

 onary sheath two lobes appear and develop rapidly, the two 

 becoming concave and surrounding the plumule as a tube. The 

 evidence in favor of a single cotyledon seems convincing until 

 this embryogeiiy is compared with that of Nymphaea, as has 

 been done by Conard. 81 In this genus the same spherical mul- 

 ticellular proembryo appears, two opposite and symmetrical 

 cotyledons with the stem-tip between them arising from the free 

 side, and the basal portion forming the hypocotyl. At maturity 

 the cotyledons become concave and inclose the plumule, just 

 as in Nelumbo. There can be no question that the two genera 

 are closely related ; and since the embryogeny of Xympliaea is 

 typically dicotyledonous, it follows that that of Nelumbo must 

 be only a modification of it, and that for some reason the stem- 

 tip does not occupy its usual central position, and the two 

 cotyledons arise for a time en masse, as in the case of petals 

 in sympetaly. Conard calls attention to such behavior on the 

 part of the cotyledons of Tropaeolum, which appear " connate- 

 perfoliate " about the hypocotyl ; and also to the fact that Hegel- 

 maier noted the complete fusion of the cotyledons along one 



