14 BULLETIN 842, U. S. DEPARTMENT OF AGRICULTURE. 
the same degree of development, become externally desiccated, mo- 
tionless, and partly coiled. In this condition they are capable of 
remaining dormant for many years. The writer has recently reac- 
tivated in water such larva? from galls which had been imported 
along with wheat from Turkestan in 1910. According to Needham 
(26), a W M. Baher" in 1771 secured vital movement in specimens 
which the former had sent him 27 years previously, in 17M. During 
this period the larva? had been kept in protective galls in the labora- 
tory. When mature galls previously soaked in water are opened, 
the larva? upon being freed immediately straighten out with a 
mechanical movement and later, sometimes within a half hour or 
occasionally only after a day or more, begin their sluggish eellike 
vital motions. The two types of movements, though distinctly dif- 
ferent and due to different causes, have nevertheless been confused 
even by trained observers. Dead larva? may show the former — that 
is, the mechanical straightening — in a manner very similar to live 
ones, but only living larva? show the vital, eellike movements. Very 
probably, however, "M. Baher" in observing the 27-year-old ma- 
terial referred to above saw both the mechanical and vital move- 
ments. 
Moistened or submerged in water the larva? move actively (PI. V, 
B), but not in the rapid manner so typical of free-living forms. 
After being held in distilled water at room temperature for more 
than two months, the writer has observed them still sluggishly mov- 
ing. During this time the only change noticeable was in transpar- 
ency, caused undoubtedly by the utilization of reserve food. The 
translucency increased with the length of time of immersion until 
finally, at the last observation, they were almost transparent. Liber- 
ated in soil under natural conditions, they are capable of living in a 
free state much longer. Marcinowski (22) concluded from care- 
fully conducted experiments that they could probably live thus in 
an active condition for seven months or more. In the application 
of control measures for the wheat nematode, as for the root-knot 
nematode {Heterodera radicicola) , use can be made of the fact that 
these active larva? will starve to death in a comparatively short 
period. 
Although capable of living free in the soil or elsewhere for several 
months, the larva? undergo no development until the host plant is 
penetrated. By their own eellike locomotion they travel through the 
soil in search of wheat seedlings, and numerous larva? finally become 
located between and within the leaf sheaths near the apical growing 
points of the culms. They may use the roots as a means of elevating 
themselves to other parts of the host, but, contrary to what Eof- 
fredi (30) and other investigators thought, do not normally penetrate 
