OPHIOGLOSSA CEX. 



379 



..hole Of its upper surface, .ith the exception, in 0. palunculoswn , of tne srnall 



•mary tuber ; In Botrych.um it is the lower side which ch.efly bears anther.d.a. 



The lntl.n,iia are cavities in the tissue of the prothallium covered externally by a 



few layers of cells, and in Ophioglossum only slightly project.ng beyond the surface. 



n this .venus the mother-cells of the antherozoids originate by repeated dwjs.ons 



,L on: or two cells of the inner tissue (covered externally by one or two layers 



of Tens) ; they form a mass of tissue of roundish form. The antherozo.ds are 



liar n form to those of the Polypod.ace*, but larger; they escape through a 



■ t\ ^th natiij-al size) ; -w roots, st stem, hs leaf-stalk, 



. . u „r ,l,e antheridium. The Archegonia are apparently 



narrow opening ur the cover of the ''"^f^^^^^^,,. Cryptogams. Mettenius 

 developed in a similar manner to *-^^ "^^ "^^^ J ^ f ^f two ^ells, a superficial 

 saw in Ophioglossum mstances m wh ch ^^J ^^ ^^^^^^ ,,, ,,„tral cell, 



cell and one lying below it; this latter, ne covering cells of the 



the former producing the necU ^^ 'f /^tTaTL p ouTdwhich are then 

 central cell arranged in the form of ^ >■-; " \^^^ ,„„,i,,„g of two or 



transformed, by further divisions, mto four vertical row 



