no 



D. H. CAMPBELL ON THE DEVELOPMENT OF THE OSTRICH FERN. 



Aboxit the time that the spoivs are fully ii'i-owii, hiit Iicrnre the exospore i.s completed, 

 the walls of tile ])arii'tal cells l)t'g"ia to assunir a hrowii tinge, this beginning with the 

 cells of the annulus, whose division walls show it first. The coloi- is at first pale yellow- 

 ish, lint the Avails darken I'apidly, until when mature they are a dark, ahnost ])ei'fectly 

 opaque brown. The contents of the parietal ci'lls disappear, leaving them dry and l)rit- 

 tle, and when ri|)e, by tiie contraction of the celli* of the annulus, the caijsnle is bui'st. the 

 o])eniug taking' place at tlu' stominm and the spores are discharged. 



Each sorns develops a small indusium (fig. 12, in), which is nearly semicircidar and 

 attached by its lower margin to the base of the receptacle, separating the soi-i. Tt never 

 attains much size and eai'ly withers away, its place being taken by the rev(tlute margin 

 III" ilu' leaf, this ])eing thin and membranaceous, consisting for nearly half its width of 

 a single layer of cells, which finally become di'v and scarious, comjiletely covering the 

 sori (figs. 10, 28). 



I'here are five sori developed upon each pinna-lobe of the fertile frond. They are at 

 lirst sessile (fig. 11), but soon are elevated upon a pedicel, from whose centi-al cells a 

 shoi't Hbro-vascidai- bundle is formed connected with the vein above which the sorus 

 arises (fig. 12). When comidete they ai'c so large that they toitch one another, so that 

 the whole lower sui-face of the leaf a]i]iears to be covered Avith s])orangia. 



COXTP]XTS. 



Int 



Si'i' 



Soo 



Sec 



Sf< 



roduction. I'.-ige 17. 



lion I. The ProtliaUiuiii. ruu'e IS. 



The spores. Germination. ConUnnity ol' Uie pro- 

 toplasm. Cliloropliyll grannies. Cell division. The 

 apical cell. Formation of tlie sexnal organs. 



tion 11. The Se.xual Organs. I'age 20. 



The autheridiiim. Cell-division of the- antheridium. 

 Antherozoids. .Escape of the antherozoids. Jlove- 

 ments of antherozoids. The arcliegonia. Origin ol 

 the archegonia. Cell-division. Neck-cells. Canal- 

 cell. Absence of ventral canal-cell. Germ-cell. Fer- 

 tilization. Dioecisni of the protliallia. Methods of 

 growing the protliallia. 



tion III. The Embryo. Fage 2(!. 



First division of the embryo. Establishment of the 

 apical cells. The first leaf Stem. Foot. Hoot. Pri- 

 mary fibro-vascular bundles. Venation of the first 

 leaf. Scales. Development of the tissues of the pri- 

 mary root. The second root. The development of 

 the tissues of the stem. Later development of the 

 young plant. 



lion IV. The Ix>af. Page ;U. 



Origin of the leaves. The apical cell of the leaf. 

 Scales and hairs. Structure of the young leaf Divis- 

 ion of the apical cell, and relation of the derivative 

 cells to the tissues of the leaf. DifleriMitiation of tlie 

 lis.sups of the petiole. Fibro-vascular bundles of l,ln' 



petiole. Development of the pinnae. Formation of 

 till! veins. Fibro-vascular bundles of the veins. Epi- 

 dermis and stomata. Development of the hairs ami 

 scales. -Vrrangemeut of the leaves. Fertile fronds. 



Section V. The Stem. Page 38. 



The apical cell. Cell division in the apical cell, and 

 establishment of the tissue systems. Cavities in the 

 ground tissue. Epidermis. Development of the libro- 

 vascular bundles. The complete rhizome. Develop- 

 inenl of the stolons. Development of the tissues of 

 the stolon. First aeri.al leaves of the stolon. Branch- 

 ing of the stolons. 



Secttion VI. The Root. P.ige 4;!. 



.Vrrangement of the roots. Apical cell. CelUlivision 

 in the apical cell and establishment of the primary 

 tissue systems. Root-cap. Development of the per- 

 manent tissues. The complete root. Secondary 

 roots. 



Section VII. The Sporangium. Pag(! 4i;. 



The ferlile frond. Young sorus. Succession of cell 

 division in the niotluu' cell of the sporangium. Arehe- 

 sporinm. Division of the ;ircliesporium. Tapetum. 

 .\nnulns. formation of the spore niother-c(dls. I5e- 

 havior of Un? nucleus of the niotlierc('ll. Develop- 

 ment of till' spor(!s. Rip(!ning anil dispersion of the 

 spores. .Arrangement of the .sori. 



