All of these methods with the exception of those of i'nien and 

 inder involve special a^^aratus often not easily available. It was 

 aecessaty for fH e -rurroses of this investigation to find a simpler 



of accomplishing the sa-ne results, '"his report therefore is 

 concerned "/ith t'vo rro ultras; first, a means of making th r: intensity of 

 monochromatic light outlined with a act of light filters equal; 

 second, a comparative study of the tronisma obtained with differ- 

 ra nt ''ive lengths when the intensity variable in eliminated. The nar- 



^henomena chosen for this study are t^ e rower of monochro- 

 matic lights to (I) establish the rolurity of ^ucus sror el incs and 

 :,he origin and consequent direction of the rhizoids; (2) to nro- 

 iuce the negative rhototr -^ism of t 1 n rhizoid; (3) to direct the move- 

 icnt?? of 1r olvox. 



, Ar>raratus and r ethods for Exposure to Monochro- 

 matic Light of Equal Intensity. 



As biologocal science oec ones more exact with the tend- 

 eouce the expression of natural -phenomena to mathematical form- 

 it is obviously essential to define stimuli of all sorts ouant- 

 Ltatively. Indefinaite or incomplete records of light stimuli can 

 10 longer bo attributed to the lack of means of measuring them be- 

 :aune access to a spectroscore ano thermopile make it possible to 

 inalyae any light qualitatively ana quantitatively. 



