ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
195 
cotyledonary growth. During the early stages the development of the 
embryo in Convolvulus is the same as that in Cuscuta, but a larger 
vacuolate suspensor is typical of the older embryos of the former. Poly- 
Embryo-sac of Convolvulus One- and two-celled embryos 
sepium, showing poly- more highly magnified, 
embryonic condition. 
embryony is the rule in Convolvulus , but no case was observed in 
Cuscuta ; the synergidal cells give rise to the numerous embryos in 
Convolvulus. In both species the endosperm is the result of free nuclear 
division. S. G. 
CRYPTOGAMS. 
Pteridophyta. 
Development of Prothallia and Antheridia from the Sex-organs 
of Polypodium irioides. — W. N. Steil {Bull. Torreij Bot. Club , 1921, 
48 , 271-7, pi. and figs.). In an old culture of prothallia of Polypodium 
irioides , the sterile cells of a large number of antheridia and archegonia 
became vegetative like ordinary prothallial cells. The lid and the ring 
cells of the antheridia produced prothallial filaments and secondary 
antheridia. The archegonia produced similarly from the neck and the 
venter cells filaments and antheridia, but in no case secondary arche- 
gonia. At some time during their course of development, antheridia 
were transformed into prothallia. No such transformations were 
observed to occur among the archegonia. The prothallia produced from 
the sex-organs resembled those formed from the germination of a spore. 
Secondary antheridia arising from antheridia and archegonia developed 
actively motile antherozoids. Unusual cultural conditions probably 
diverted the sex-organs of Polypodium irioides from their normal course 
of development. No similar case of regeneration has been previously 
reported in a Pteridophyte. A. Gepp. 
Synopsis Hymenophyllacearum. — R. B. van den Bosch and W. A. 
Goddijn ( Mededeelingen Rijks Herbarium Leiden , 1913, No. 17, 36, 
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