238 BOARD OP AGRICULTURE. 



the warm weather is fairly begun ; but then the animalcules begin 

 to find their way from the blighted grain into the earth and thence 

 into the young grain. They gradually ascend within the stem till 

 they reach the ovule (or young state of the seed) in the flower- 

 bud, even before the ear has shown itself. The young are hatched 

 in about eight or ten days after the eggs are laid, and speedily 

 attain to about the one thirty-third of an inch in length, and the 

 one twelve-hundreth of an inch in diameter. When full grown, 

 the vibrio acquires a monstrous size compared with one of the 

 multitude which composes the cottony mass in the blighted grains, 

 becoming a quarter of an inch long, and the one-eightyeth of an 

 inch in diameter. The most curious circumstance which observers 

 have noticed in the economy of this animal is the wonderful 

 property it possesses of retaining its vitality under conditions in 

 which we should have supposed it impossible that it could have 

 lived. If a mass of them is suffered to become so perfectly dry 

 that the slight touch of a hair might reduce them to powder, and 

 they are again moistened in a drop of water, they will speedily 

 revive and become as active as before. They may be thus dried 

 and revived many times before they are killed. " It does not appear 

 that the vibrio naturally attacks any other grain than wheat." 

 Scalding water kills the vibrio, and this suggests the possibility 

 of exposing infected samples to a temperature that might be 

 sufficiently high to kill these animalcules, without being so hot as 

 to destroy the germinating powers of the grain. 



The wheat midge is an insect infecting wheat. It has been so 

 well studied by American entomologists, and so many valuable 

 treatises upon it have been placed within your reach, that I shall 

 not trespass upon your time to speak now of its nature and habits. 

 The valuable practical entomology now being published by Dr. 

 Packard of .Salem, is an excellent guide to all desirous of study- 

 ing the diseases produced by insects. 



Dr. Packard was formerly attached as entomologist to the State 

 Survey of Maine, and his " Guide to the Study of Insects" is ex- 

 ceedingly well adapted to the wants of Maine farmers because 

 the author is so familiar with the insects of his native State. 



There are two plant-diseases produced by insects which must be 

 alluded to under this head. Galls and Stunted Spruce. The first 

 is an affection of the oak and willow leaves. "A minute insect 

 wounds the bark and leaves while depositing its ova, or eggs, and 

 the irritation excited causes tlic formation of a deposit around 



