352 
On Purples or Ear-Cockle in Wheat. 
Soon after the mother-worm has completed the lad ing of the 
eggs she dies. By the time that the crop is ripe and the galls 
have attained their maturity the whole of the eggs have been 
hatched, and a section of the full-sized gall contains within the 
thickened walls only a cotton-like mass of minute worms (Fig. 6). 
Fig. 6. — Full-sized Galls, external aspect and section, showing the dense 
cottony mass of Worms filling the interior. 
As long as the galls are kept dry the worms remain in a 
torpid condition. They are able to retain their vitality for a 
long time, but when the gall obtains a supply of water the 
worms become active ; they penetrate the wall of the gall and 
escape. Even after they have left the gall they may be dried 
up and become torpid, and remain in this condition for a con- 
siderable time without being killed, for when moisture is applied 
to them they revive again. 
The careful consideration of these facts in the history of this 
disease of the wheat will convince the reader that great pre- 
caution should be exercised in preventing any of the galls being 
sown with the seed. For each gall sown may supply tens of 
thousands of worms, ready to prey on the young wheat plants. 
The attack is made when the crop is only a few weeks' old. 
It might be expected that in the case of winter wheat the frosts 
would kill these thin-skinned delicate worms. No doubt 
many thus perish ; but intense cold, like complete desiccation, 
does not succeed in killing them. They may be enclosed in 
solid ice, and yet after the ice is melted they begin to move 
about in the water. The power of such worms in resisting the 
severest cold is strikingly manifested in the case of a grass 
brought from the Arctic regions in 1850 by Captain Puller. 
This grass had been attacked by vibrios, and several galls were 
found among the grains. These galls were brown, hard, and 
flask-shaped, with a white-tipped neck like that of a Florence 
llask. The walls of the cells were hard and thick, and the 
interior was completely filled with a white cotton-like pellet 
consisting of an infinity of little worms, with a few eggs scat- 
tered among them. The worms were smaller than those found 
