NOTE ON THE DETECTION OF SEGREGATION BY 

 EXAMINATION OF THE POLLEN OF RICE. 



By F. R. PARNELL. 



(With Plate XXI.) 

 Glutinous Rice. 



For several years a study has been in progress on the inheritance of 

 the (so-called) glutinous character typical of a small group of cultivated 

 varieties of rice. These varieties differ from the ordinary starchy type 

 in that the grain becomes gelatinous when cooked in water, so nmch so 

 that if boiled in the ordinary way the result is a sticky mass resem- 

 bling glue. 



Glutinous grains can be distinguished by their appearance since the 

 endosperm is dead white, giving a fracture like porcelain, whereas in 

 starchy gi'ains it is always more or less translucent. 



Microscopic examination of sections of the endosperm shows no 

 marked difference between the two types, the cells in both cases being 

 filled with the highly compound starch grains characteristic of rice. 

 The action of iodine, however, brings out a very sharp distinction — the 

 starch gi-ains of ordinary starchy varieties take on the usual deep blue 

 colour, whereas those of glutinous varieties become reddish in dilute 

 iodine, passing through wine colour to dark brown as the strength of 

 the solution is increased. The same difference is seen when grains are 

 broken across and dipped into iodine solution. 



The production of a reddish colour with iodine is characteristic of 

 amylodextrine, a rare form of starch that occurs in mace, and it is pre- 

 sumably the presence of this form of starch that gives to glutinous rices 

 their special character. 



Inheritance. 



In inheritance the glutinous character behaves as a simple recessive 

 to starchy but, siijce double fertilization takes place, the endosperm is a 

 fertilization product and the usual complication of results is obtained. 



Thus when flowers of a glutinous plant are fertilized with starchy 

 pollen they produce grains with starchy endosperm. An F^ plant, selfed, 



