738 Hens low .— The Origin of Monocotyledons from Dicotyledons , 
16. Cytological and Embryological Investigations. 
Some important researches have been made in the more minute details 
of embryology, which bear upon this subject. 
Messrs. W. Lubimenko and A. Maige have published an article en¬ 
titled —Recherches cytologiques sur le developpement des cellules-meres dn 
pollen chez les Nympheacees. 
‘ Independamment des caracteres morphologiques et anatomiques 
bien connus, certaines particularites cytologiques, comme la grosseur des 
noyaux et la simplicity de la membrane des grains de pollen, rapprochent 
cette famille des Monocotyledones. . . . Les etudes cytologiques faites 
jusqu’a present sur le developpement du pollen . . . ont permis d’etablir 
des caracteres distinctifs assez constants entre les Monocotyledones et les 
Dicotyledones, et elles peuvent fournir, de cette maniere, des documents 
suffisants pour la comparaison avec les Nympheacees.’ 1 
In conclusion the authors add :— 
‘ Les deux especes [Nymphaea lute a and Nuphar luteuni) se rapprochent 
des Monocotyledones par la nature simple du reseau au stade de prosynapsis 
et par la dissociation prdcoce des cellules-meres du pollen.’ 2 
Mr. Melville T. Cook has written upon the Embryogony of some Cuban 
Nymphaeaceae. 3 The following is a brief analysis of his paper bearing on 
the present subject:— 
Mr. Lyon, describing Nelumbo , considers it should be classed as a Mono¬ 
cotyledon. Cook strengthened his view with Castalia odorata and Nuphar 
advena\ Schaffner does so by comparing Nymphaeaceae with Helobiae, 
observing that the number and arrangement of ovules connect the order 
with Monocotyledons. 
The formation of the tube-sac in the embryo-sac is like that of Saururus 
(Piperaceae) (aquatic). 
The mention of Saururus at once suggests Peperomia . Species of this 
genus have been described by Mr. Hill 4 and others. Miss Sargant quotes 
details as follows :—‘ There are two cotyledons present in the seed. One is 
hypogeal and acts as a sucker (comparable with Trapa , Cyclamen , Elettaria , 
Palms, &c.), the other has assumed the appearance and functions of a foliage 
leaf. It is geophilous in structure. ... Its seedlings seem to germinate in 
the spongy herbage of the locality.’ 5 
Mr. Cook calls the ‘ tube-sac ’ a ‘ nucellaf tube ’. It extends from the 
antipodal to the chalazal end of the ovule. It originates as a great mass 
1 Rev. Gen. de Bot., xix, 1907, p. 402-3. 2 Idem, p. 499. 
3 Bot. Gaz., xlii, 1906, p. 376, PI. 16-18 ; with Bibliography. 
4 Morphology and Seedling Structure of the geophilous species of Peperomia , together with 
some views on the Origin of Monocotyledons. Ann. of Bot., xx, 1906, p. 395. 
B The Seedling Structure of some Piperales. Ann. of Bot., xx, 1906, p. 161. 
Miss Sargant discusses the embryology of P. pellucida in her Reconstruction, etc. (op. cit., 
p. 128). 
