- .J, ..1, io. lii olio iOi'Vo oi' ik; piucuHoci Uetv/een Liio 

 cells on eacli side derived iron the niicrc^sr.'rranr^iiija mol. 

 cells. From cerLain oi' thes . luiial coils, in ;. v/ay to be 

 described in detail later, are forael tno T)lacentarbnn- 

 dle and the placental branch. 



Meiinv'hile the iimer and outer Indus ial cells, on eacii 

 side of -6 so -us, h.ave kept pace with the growth of the 

 sporangial colls. Tlie acroscopic part of section V and 

 the acroscopic marginal cell liare each split "by a trans- 

 verse anticline (Fig« 53) to form the lateral part of the 

 outer layer of the Indus ia of the adjaccnl sori, and 

 these, in coiinection v/ith the cells of section II , 

 complete the outer indusial la^ -.. , surrouj^ding the sorus 

 through its vhole length (o.ind.. Figs. fiA, ,^^0 - ^2). 

 The lateral imiei- indusial cells, arisin-; from the "basi- 

 scopic marginal ell, togetlier • Ith the cells of th.e basi- 

 scopic half of section V complete tiie iujier layer of 

 :he Indus ium also. El.cIi of these layers ror.-iains of a 

 single layer in tliickness even at maturit^;,ac, no division 

 walls are fonned in their cells excepts tiiose perpindicul.r 

 -I-.o tlie suj'face, and by grov/tli in this mariner tlie indusivm 

 constantly increases the size of the soral c.vities as '. 

 ".r,c-;jigii, are pushing out in o hem (F. . - '') . Du- 

 ring the grov/th of the indusiom some intercellular spaces 

 appear, bet-yeen thn t-.r Ir.-nrs, but tiiey ;.re 1 ■ 



