1847.] Potato Disease. 341 



rail road, some of which are many feet below the usual surface, 

 are all infected. One attribute of the soil I feel quite convinced 

 has considerable influence over this disease, viz., its moisture. I 

 have planted some potatoes in a line, part of which are among 

 Gooseberry bushes and very damp; the other portion is very dry. 

 In the former the potatoes are nearly all diseased, in the latter 

 they are nearly all sound. With regard, then, to the nature of 

 this disease. I think we may fairly define it " gangrene of the 

 plant, occurring in the first instance in isolated patches either in 

 the leaves and stem alone, or simultaneously in the tuber, which 

 if left alone will ultimately destroy the plant and tubers entirel}." 

 Nearly 200 years ago Sydenham described a species of cholera 

 affecting the human subject in August. Popular error has gener- 

 ally attributed this disease to the plum season; but this is a great 

 mistake. The disease described by Sydenham may have been 

 studied by many observers, in 1847, without a variation in the 

 symptoms. It occurs in those who do not eat plums, and the dis- 

 ease caused by plums is not that described by Sydenham. It is, 

 in fact, one of those periodic phenomena of which we know little 

 more than its appearance and disappearance at certain seasons of 

 the year, and which we judge by analogical reasoning is caused 

 by some or other of those little understood, or rather little studied, 

 laws which belong to the science of meteorology. That the po- 

 tato disease belongs to the same class of diseases must, I think, be 

 perfectly clear. It has all the characters, all the variations, and 

 all the obscurity of a periodical epidemic. We may describe it 

 as " Morbus niger — a gangrene of the tissues of the potato plant 

 occurring epidemically in August; the diseased parts generally 

 covered with a fungus, which appears subsequent to the disease. 

 More extensive in cold and damp situations." More than this, 

 so far as regards the etiology of the disease, I do not think we 

 shall ever know. — Gardener's Chron. 



ADDENDA TO OUR TABLE OF TEMPERATURE. 

 July 20. — Thermometer stands at 90. Potato vines begin to 

 die South and West. 



August 4. — Potato vines commenced dying in Albany. The blight 

 in apple, quince and pear trees seems to be nearly checked here. 



December 15-23. — The temperature of the air has varied from 

 20 to 12 below freezing, while the temperature of the earth four 

 feet below the surface has remained nearly stationary at 46°5. 

 The temperature of the clay banks is three or four degrees higher 

 at the same depth than the ordinary soil. 



Note.— It is probable that many errors may be found in the foregoing ta- 

 bles, as our health has been such that we have been unable to give them 

 that attention they mer''t.. 



