No. 454-] STUDIES OX THE PLANT CELL. 



firmino- the conclusions of Mottier thai ihc^c 

 developed here after the same methods as m \v 

 cell, from surrounding investments of fibi aiu 

 trosomes. Indeed the embryo-sac is rt-mai kal)lc 

 tity of the cytoplasmic fibrillar present dunn- its ■ 

 In concluding this account attention ^liould 

 some forms whose microspore niotlu i -cells wen 

 posed to omit the mitoses oi spoioL^eiiesis and (K, 

 into pollen grains. These conditions wei e i epm t 

 the Cyperaceai, and the Asclei)ia(laeea'. lh)\\e\r 

 finds the two mito.ses present in Carcx anita, 

 the nuclei break down and the cytoplasm is aj)])!* 

 fourth to form a single pollen grain whose wall 

 from that of the mother cell The histoiy is \- 

 the development of the megaspore in certain heler( 

 dophytes {e.t^., Marsilia, Selaginella) and to tlv 

 which functions while its companion polential nu-. 

 crate. The development of the pollen in the Ase 

 been shown to be normal in the nuclear activit 

 investigators (Frye, : oi, Strasbui,i;er, : or, and ( la.L 

 tetrad consisting of four pollen -lams m a row, i 

 usual arrangement. In Zostera (Ro.enbeiL,. : oi^i 

 gitudinal divisions of the ver) much elon-aled p 

 to give four extraordinary tilitorm i)ollen giam>. 



This remarkable type of cell has lea 

 high state of development in eeitaiii jna 

 Siphonales and the hlanientuu.-, rii\toiii\ 

 rolegniales and Perono>p:)ia!e>». ( " 

 cells. The simplest tvpe- aie de\ J-;h d 

 or fragmentation of a nucleus aMoinpaiin 

 si/e of the cell but w ithout exlended 



nodal cells of the C'haracea^ and in .'Id pai 

 higher plants. 



