[34] "Ground that has not been disturbed for some hundred years, on being ploughed, has frequently surprised the cultivator by the appearance of plants which he never sowed, and often which were then unknown to the country. The principle has been ascertained to be capable of existing in this latent state for above 2000 years, unextinguished, and springing again into active vegetation, as soon as planted in a congenial soil.

"In boring for water near Kingston on Thames, some earth was brought up from a depth of 360 feet, and though carefully covered with a hand-gla.s.s to prevent the possibility of other seeds being deposited on it, was yet in a short time covered with vegetation.

"Turner says, from the depth, these seeds must have been of the diluvian age."--_Jesse's Gleanings._

[35] Hamilton's History of Medicine, vol. ii. p. 276, note.

[36] "What I wish you to remark is this, that while almost all men are p.r.o.ne to take the disorder, large portions of the world have remained for centuries entirely exempt from it, until at length it was imported, and that then it infallibly diffused and established itself in those parts."--_Dr. Watson on the Principles and Practice of Physic._

Dr. R. Williams says, "The seeds of intermittent fever lay dormant for months, it was not at all uncommon for cases of intermittent fever to be brought into the hospital eight or ten months after the patients had subjected themselves to the influence of paludal or marsh effluvia."

[37] I have observed in the hot-houses, that many of the exotic plants, which are in company with the diseased vines, have been attacked, while others again have been entirely free.

[38] By causes of the greatest variety plants may become extinct for a time. It is not very easy to trace them, but one fact may be mentioned in proof of the statement. Dr. Prichard states that vast forests are destroyed either for the purpose of tillage or accidentally by conflagrations. "The same trees do not reappear in the same spots, but they have successors, which seem regularly to take their place. Thus the pine forests of North America when burnt, afford room to forests of oak trees."

[39] Hecker says of Chalin de Vinario, that "he a.s.serted boldly and with truth, that _all epidemic diseases might become contagious, and all fevers epidemic_,--which attentive observers of all subsequent ages have confirmed." P. 60.

[40] In 1539, the thirty-first year of Henry the Eighth, was great death of burning agues and flixes; and such a drought that welles and small rivers were dryed up, and many cattle dyed for lacke of water; the salt water flowed above London Bridge.--_Stowe._

In 1556, the fourth of Mary, and the third of Philip, about this time began the burning fevers, quarterne agues, and other strange diseases, whereof died many.--_Stowe._

The next winter, 1557, the quarterne agues continued in like manner, or more vehemently than they had done the last yere.--_Stowe._

[41] Every writer on the climate of Egypt has remarked, that the Endemic Fever which is so frequent, originating on the coast, particularly about Alexandria, becomes occasionally so virulent, that it cannot be distinguished from the _true Plague._--_Robertson on the Atmosphere_, vol.

2. p. 384.

"Endemial Fevers of every situation become occasionally so aggravated, that they cannot be distinguished from such as originate from contagion; and in every unusual virulence of this Endemic Fever, it is probable that it may be propagated afterwards by contagion as every epidemic." _Ibid._ p. 388.

[42] Dr. Ure.

[43] "The metamorphosis of starch into sugar depends simply, as is proved by a.n.a.lysis, on the addition of the elements of water. All the carbon of the starch is found in the sugar; none of its elements have been separated, and except the elements of water, no foreign element has been added to it in this transformation."--_Liebig_, _Organic Chemistry_, p. 71.

[44] As regards starch there appears to be some peculiar faculty regarding it. It is converted into sugar during the ripening of fruit, and it is just possible that being as it is of a cellular nature, the property of vitality may attach to it until it has, by being converted into sugar, fulfilled its destination.

[45] Though I do not consider that the fermentation process is a fac-simile of diseased action, yet I think its phenomena generally afford an apt ill.u.s.tration of the changes which may be effected by living germs. Many able chemists still maintain the entire dependence of fermentation upon the Torula: "M. Blondeau propounds the view that _every kind_ of fermentation is _caused_ by the development of fungi."

The varieties of opinions found in the literature of this subject, forms a curious specimen of scientific enquiry, and is sufficient alone to convince us of its vast importance and extensive relations.

[46] By Dr. Mantell.

[47] Mitch.e.l.l on Fevers.

[48] We wonder, and ask ourselves: "What does SMALL mean in Nature?"--_Schleiden's Lectures on Botany._

[49] Speaking of the bunt in wheat: "It appears certainly to be contagious, from numerous experiments, which shew that the contagious principle lasts a long time. I have tried it myself; some, however, doubt it, but it cannot be denied, that seed sown, infected with bunt, produces plants similarly affected; every one who has had the slightest experience must be convinced of it."--_Essay on the Diseases of Plants._ _Count Re._

[50] We have already spoken of the effects of these poisons, and have stated that the amount of each poison capable of destroying the body is pretty accurately known.

[51] The italics are my own.

[52] Gmelin says: "But the mode of action in these transformations, sometimes admits of other explanations; and when this is not the case, our conception of it is by no means sufficiently clear to justify the positive a.s.sumption of this, so called contact-action or catalytic force, which, after all, merely states the fact without explaining it"--_Gmelin's Hand-book of Chemistry_, vol. i. p. 115.

[53] The history and symptoms of some epidemic diseases, such as cholera and influenza, are not inconsistent with the hypothesis that they are caused by the sudden development of animalcules from ova in the blood. But there is a total want of direct observation in support of this hypothesis.--_Dr. Williams' Principles of Medicine._

[54] Since writing the above, I have referred for information on this subject, and find, that the Anguillula aceti exhibits s.e.xual distinctions; and that the ovaries of the females are situated on each side of the alimentary ca.n.a.l.--_Cyclo. Anat. and Phys. Art. Entozoa._

[55] Speaking of the examination of the infusory animalcules--Mr. Kirby says: "But to us the wondrous spectacle is seen, and known only in part; for those that still escape all our methods of a.s.sisting sight, and remain members of the invisible world, may probably _far exceed those that we know_."--_Bridgewater Treatise_, vol. i. p. 158.

[56] Mr. Owen has added another cla.s.s, as the first, called Protelmintha, which comprises the cercariadae and vibrionidae.

[57] "It is probable that in the waters of our globe an infinity of animal and vegetable molecules are suspended, that are too minute to form the food of even the lowest and minute animals of the visible creation: and therefore an infinite host of invisibles was necessary to remove them as nuisances."--_Bridgewater Treatise_, vol. i. p. 159.

"When Creative Wisdom covered the earth with plants, and peopled it with animals, He laid the foundations of the vegetable and animal kingdoms with such as were most easily convertible into nutriment for the tribes immediately above them. The first plants, and the first animals, are scarcely more than animated molecules,* and appear a.n.a.logues of each other; and those above them in each kingdom represent jointed fibrils."+--_Bridgewater Treatise_, vol. i. p. 162.

* Globulina and Monus. + Oscillatoria and Vibrio.

[58] "A treatise which should present a systematic arrangement of all the diseases of plants, giving in detail the exact history of each, and adding the means of preventing and curing them, would certainly be of the greatest utility to agriculture." --_Essay on the Diseases of Plants, Count Philippo Re, translated into Gardener's Chron._

[59] "Plenck published a treatise on Vegetable Pathology, in which he divided diseases into eight cla.s.ses: 1. External injuries; 2. Flux of juices; 3. Debility; 4. Cachexies; 5. Putrefactions; 6. Excrescences; 7.

Monstrosities; and 8. Sterility. And he concludes with an enumeration of the animals which injure plants."--_Essay on the Diseases of Plants, Gardener's Chronicle._

[60] The Bunt. "This disease appears at the moment of the germination of the plant. The affected individuals are of a dark green, and the stem is discoloured. As the ears are issuing from the sheaths, their stalks are of a dark green, but very slender. When the ear has fully grown out, its dull, dirty colour, causes it to be immediately distinguished from the healthy ones, and it soon turns white."--_Essay on the Diseases of Plants._

[61] _Vidi_ understood.

[62] "At the close of the year 1665," says Dr. Hodges, "even women, before deemed barren, were said to prove prolific."

"After the cessation of the Black Plague, a greater fecundity in women was every where remarkable--a grand phenomenon, which from its occurrence after every destructive pestilence proves to conviction, if any occurrence can do so, the prevalence of a higher power in the direction of general organic life. Marriages were almost without exception prolific; and double and treble births were more frequent than at other times."--_Hecker_, p. 31.

[63] It is stated that on the decline of the Plague, 1665, those who returned early to London, or new comers, were certain to be attacked. In proof of this the 1st week of November, the deaths increased 400, and "physicians reported that above 3000 fell sick that week, mostly new comers."

See also Dr. Copland's Dict. Pract. Med. Epidemic and Endemic Diseases.

"The hardy mountaineer is a surer victim of paludal fever, whether he visits the low countries of the tropics, or the marshes of a more temperate climate, than the feebler native of those countries."--_Dr. R. Williams on Morbid Poisons._

[64] "Substances presented to the gastro-intestinal surfaces, are mixed up with various secretions, mucus, saliva, gastric juice, bile, pancreatic liquor, and special exudations from the peculiar glands of each successive section, while aerial poisons, unmixed and unfettered, are applied at once to a surface on which, behind scarcely a shadow of a film, circulates the blood prepared, by the habitual action of the respiratory function, to absorb almost every vapour, and every odour, which may not be too irritating to pa.s.s the gates of the _glottis_."--_Mitch.e.l.l on Fevers._

[65] Hecker on the "Black Death."

[66] The stomach in some cases is no doubt the medium by which some diseases are contracted. It is well known, that in many places the water induces diarrhoea, the permanent residents, however, may not suffer, but all new comers are more or less affected by drinking it.

[67] "Similar effects have been experienced from the use of mouldy provisions."--_Dr. Lindley's Vegetable Kingdom._

[68] "Untold numbers die of the diseases produced by scanty and _unwholesome food_."--_Southey._

A large, nay, a most extensive adulteration of flour with plaster of Paris was detected not many years since. The flour was supplied by a contractor for the manufacture of biscuits for the navy.

[69] See Southey's Doctor, vol. ii. interchapter vi. p. 115, for an ill.u.s.tration of this subject.