-i-Ct^Yrt/ma/W 



TO summarize briefl" '. .is work on light and chemical stimu 

 li as they affect the polarity of ^ucus e .d the direction of 

 growth of the rhizoida: 



(1) Green, blue, 8$rt violet "-ight (4000-5609 A.n.) of an inten- 

 sity great enough to produce negative phototropisms of the growing 

 rhizoids is without effect on the direction of the first cleavage f 

 plane of the egg. 



3 



? N 

 > J 



chemical stimulus which orients the direction of the 



first cleavage plane and determines which cell shall become ths 



rhizoidal cell 



alli 



diet 



vhemi 



' ~-' hrig no power to ^s&r,. c cf 



rhizoids . 



()Th laxative photctropism or the rhizoicr : . *i .^o- 



.. ~ c ' _ . '. .' , . "^ " .a_. ^ 13 



since, with equal intensity of illumin; ." ;ht 



: peel . Lthoti ^ 



j - 



