This subject has probably been before you at every meeting since the organization of the society, and in looking over the proceedings we feel very much like a member who said at a meeting as long ago as 1855, " I have read a wheelbarrow load of books on the subject and have learned nothing," and in a recent publication we find: "Now, Mr. Editor, I have a firm belief that nobody knows anything about this disease more than another, and it is a waste of time to listen to anybody's say about it." Hoping your society will pardon me for adding another "straw,"' I will be as brief as possible.

The progress made toward discovering the cause of pear "blight" has certainly appeared very slow to those who have been compelled to see their trees stricken down under the best (?) of care, nearly powerless to prevent the spread of the disease.

Nearly every writer on pear culture in the past, has advanced different theories as to the cause and treatment of the disease, variously termed "fire blight," "sap blight," "frozen sap blight," "insect blight," "summer blight," "winter blight," etc.

Insects were often accused of being at the bottom of all the trouble, and we are not quite ready to give them a verdict of acquittal. They are charged with aiding in spreading the poison, and for many it would be hard to prove an alibi.

Electricity was believed by some to be the cause, with plenty of argument to back it. The appearance of "blight" after a thunder shower is a well known fact, which would .appear as conclusive evidence.

The theory that the freezing of sap in a healthy branch will cause "blight" is still prevalent. Tender or unripe shoots often suffer or are killed by sudden freezing and thawing in the sun, causing, however, a different effect from the so-called blight. A blighted spot, the size of a hand, often found on the trunks of trees, would be difficult to explain by the "frozen sap" theory.

I do not believe that sap ever freezes in a healthy tree. Frost extracts moisture from the plant cells, and if the roots do not extend below frost, or where they can supply the deficiency, the bark shrivels, and the tree often dies.

It was left for the microscope with its modern improvements, and to the accuracy of investigations made with it, to reveal the true nature of the mysterious disease. In a letter to the Gardeners' Monthly (August, 1875), Dr. Hunt says: "I have examined those pear branches, and find that the black color is caused by a fungus. * * * I cannot name the fungus. Repeated observations only can determine that question. * * * I have made thin sections of stem, bark, fruit and leaves' and removed excess of black color until I could send daylight into every cell; and then under * 500 the parasite reveals its presence."

For the next five years little progress seems to have been made, except that the German and French naturalists, principally Cohn, Magnin, Pasteur, and Frische, continued to publish their experiments and discoveries. In 1880, Professor Burrill announced that "blight" in the pear, apple, and quince was caused by bacteria, the smallest living organism known. He found that they destroy the stored starch grains, causing the same to ferment, leaving the cell structure apparently unharmed.

With the poisoned sap he inoculated healthy trees, of which over sixty per cent. showed signs of "blight," clearly proving that bacteria is the cause and not the effect of the disease. No counter evidence has been brought against these experiments of two years ago.

About twenty years ago, Derlaine stated that bacteria belonged to the vegetable instead of the animal kingdom, as was the belief up to that time, and only a few years since it has been proven that they attack and destroy living matter. They increase by "fission," dividing in the middle, under favorable circumstances, once every hour, and sometimes even oftener. Once an hour would be at the rate of sixteen and a half million in twentyfour hours. A few species are also perpetuated by spores, like fungi. The most favorable temperature for their rapid development appears to be about 950 Fahrenheit, together with plenty of moisture.

Prof. Burrill is of the opinion that this kind of bacteria (Microcosus amylovorus B.), is rarely found floating in the air, being extremely viscid, and usually mucilaginous, when moist. In this condition they would be readily carried about by insects. The most likely to aid in their dissemination would be the true bugs (Hemiptera), who obtain their food by the use of a sharp beak, with which they puncture the bark to suck the sap, and by coming in contact with the sticky, poisonous fluid, may carry it from one branch or tree to another.

The following is Burrill's description of the species: