Randolph and I : ^rce(l905) performed *m one-sided illumination 

 experiments on Sicbyota. JJictyooteris. Lanrencia, and Gystoseira, 

 and poinl^out the certainty of the j^/diium-jy action of other factor 



because rhizoids are formed in .he dark and in all-sided illumin- 

 i 



ation. They say that although Y/inkler (1900) suggest^ tne possibility 

 of stopping germination toy changing the direction of lign-; every 

 three hours, i ; could not be done with Sictyopteris. They emphasized^ 

 theroossibility of influences preceding the illumination affecting 

 tr:e polarity. 



The work of Fronrne'Rev. 1914) on the urediniospores of Puccinia 



rhamnif shauid oa men-. ioned horo/. He *&* that in darkness the 



^ U 



germ tube grew from any side^oT the spore, but that in inilateral 



e tubes almost always issued from the darker side of the a* 

 spore. 



