212 Detection of Sefiregation of the Pollen of Rice 



its presence and absence, or the presence and absence of other substances 

 recognizable by microchemical tests. This line of work appears to offer 

 distinct possibilities from the point of view of determining the stage at 

 which segregation takes place, especially if such dimorphism can be found 

 in a species in which the pollen grains remain united in tetrads. 



DESCRIPTION OF PLATE XXI. 



Iodine Reaction of Starch in Pollen Grains. 



Fig. 1, Anther of s((rr(;/H/ type, pollen all dark. 



Fig. 2. Anther of glutinous type, pollen all light. 



Fig. 3. Anther of -P'l , pollen mixture of dark and light. 



Fig. 4. Part of Fj anther more highly magnified. 



Fig. 5. Free pollen of Fi showing two types. 



