ORIGIN OF POLARITY, SYMMETRY, AND ASYMMETRY 6] 



Fig. 23 

 Electrical control of primary polarity in the eggs of the brown alga Fuciis. Two- 

 cell stages, a, Eggs subjected to appropriate current density. They are practically 

 all oriented with the smaller end towards the^anode. b, Eggs serving as control, 

 subjected to current density below the threshold requisite to secure orientation 

 (equivalent to a fall of 0-025 volt across the egg). The eggs point at random. 

 (From Lund, Bot. Gaz. lxxvi, 1923.) 



