NEMATODE GALLS IN MARKET WHEAT. 



and wrinkled. Usually they are shorter and broader than sound 

 wheat kernels, but sometimes are equal in size, or again may be very 

 narrow and needlelike. Very small galls, the size of wild buckwheat, 

 are also found frequently. It is not uncommon to find several of 

 them tightly cemented together. 



In color the galls vary from a light gray to a jet black. Usually 

 they are dark brown but may also be mottled to some extent. 



The covering of the gall is very thick, making up some 95 per cent 

 by weight of the entire gall. It incloses a yellowish-white powdery 



Pig. 3. — A transverse section of the nematode gall, showing worms and 

 outer thick husk. X35 



substance, which, when moistened with water and placed under a 

 magnifying glass, is seen to disintegrate into small thread-shaped 

 worms about two-tenths of an inch in length and two-thousandths 

 of an inch in width and slightly decreasing in size at each end. 

 Figure 3 is a transverse section of one of the galls magnified to show 

 the thick covering and the inner powdery substance composed mostly 

 of small worms. 1 Figure 4 is a photograph of one of the nematodes 

 or eel worms highly magnified to show its structure. 



The galls, upon falling to the ground, decay under favorable mois- 

 ture and temperature conditions. The nematodes then escape, and, 



1 The Bureau of Markets wishes to express its gratitude to Miss B. H. Silberberg, 

 Bureau of Chemistry, for the photomicrographs of figures 3 and 5. 



