Dr. Wright believes that there is no che mical difference (or, rather, none admitting of detection) between healthy saliva and that secretion which is capable of producing hy drophobia. He has succeeded in producing rabies by injecting healthy saliva into the veins of animals, and it appears probable from his observations, that the difference between saliva capable of producing hydrophobia, and the fluid in its normal state, must be regarded rather as one of degree than in kind.
Infection.—Saliva is said to have produced disease by contact in a variety of ways ; with how much truth appears most uncertain, but the following statements are related as mat ters of fact :— Syphilis is said to have been communicated by kissing, and by the morbid saliva adhering to a drinking cup. Lassius, Wedelius, and Victor Schneider are of that opinion. Phthi sis, according to Bernhard Gladbach, has been communicated by means of the saliva ; and scurvy, also, according to Rolfincius, Senner tus, and 141ichael. Ledelius states that an old woman infected a boy with ague by giving him bread to eat which she had previously mumbled. Many other equally strange and disgusting statements of this kind have been put forth by old writers, which show little else than the imperfect method of inquiry which satisfied the older investigators, and a lamentable inclination on their part to re gard coincidences as of necessity bearing the relation of cause and effect.
The saliva is stated to become coloured occasionally, but the subject requires further investigation. Drs. Thomson and Christison have noticed it of a blue colour under the use of lead, and Dr. Wright says that ordinary medicinal doses vvill produce that effect. The same observer has noticed a deep blue co loured saliva in purpura and advanced stages of fever, and is of opinion that prussian blue is the cause, but has not yet examined the point. Great acridity of saliva has been ob served in maniacal patients. Dr. Wright has recorded that such saliva is sometimes so irritating as to be capable of excoriating the hand when applied to it.
Children's saliva may become so acrid as to excoriate the nipples of any nurse who may suckle them.
.2VIercurial Salivation.— Simon has obtained acetic acid from saliva discharged during sali vation, and believes it may also exist in rheu matism. Donne says the saliva becomes acid in many forms of disease. Brugnatelli found oxalic acid in the saliva of a phthisical patient. The following is Simon's analysis of the saliva of mercurial salivation (it contained acetic acid which was volatilised during evaporation): Water - - - - - 974.12 Yellow viscid fat - - - 6.94.
Ptyalin, extractives, and traces} 3.60 of casein - Alcoholic extractives, and salts - 7.57 Albumen - - - - 7.77 This saliva, therefore, differed from that of health in containing excess of solid constitu ents, arising from excess of fatty matter, ex tractives, albumen, and salts. The ptyalin remains much as in health.
L'Heritier gives the following as the mean of three analyses of the saliva in mercurial salivation.
Water - - - 970.0 instead of 986.5 health.
Organic matters 28.6 „ 12.6 Inorganic matters 1.1 „ 1'9 L'Heritier, like Simon, found no great va riation in the amount of ptyalin.
Dr. Wright found a great increase in the quantity of mucus contained in the saliva dur ing mercurial salivation. He could not detect mercury in the secretion. His analysis is as follows : Water - - - 988.7 Ptyalin - - - - - 1-9 Fatty acid Albuminate of soda - - - 0.6 Mucus, with a trace of ptyalin - 3.8 Lactates Phosphates I. potash } Hydrochlorates soda 2.4 lime Hydrosulphocyanate Gmelin found a considerable variety in the saliva of patients who had been salivated by mercurial inunction. In one case a large quantity of fat was detected by him. He obtained mercury from this saliva.
Spontaneous Salivation. - The saliva of spontaneous salivation has been examined by Vogel, who found it constituted as follows : Water - - - - 991.2 Ptyalin, osmazome, fat, and 4.1 albumen - - Salts of soda, potash, and lime 4.4 This shows no great variation frorn the na tural standard.
Mitscherlich and Guibourt, who also ex amined the saliva of spontaneous salivation, found no increase in the solid constituents, while the sulphocyanogen and ptyalin were deficient.
Simon examined the saliva of a patient suf fering from inflammation of the pancreas (?). It was a clear viscid fluid secreted in great abundance. It contained mucus, and was of alkaline reaction. Its specific gravity was 1005.
Under the microscope, numerous oil ve sicles were visible, besides ordinary mucus, globules, and epithelium scales ; 1000 parts of this saliva yielded 10 parts of solid matters.
L'Heritier examined the saliva of chlorosis, and found it to suffer from watery degenera tion, in the same manner as the animal tissues and secretions generally.
In dropsy, with albuminous urine, the saliva was found by L'Heritier to contain, Water - - - 985.9Organic matter - - 13.6 Inorganic matter - - •5The amount of water contained in saliva appears to diminish in inflammatory affections. The following is a mean result obtained from six analyses made on the saliva of cases of in flammatory fever, pneumonia, and erysipelas : Water - - - 968-9Organic matters - - 30-0 Inorganic matters - 1.1 The proportion of ptyalin was found in creased.
Scherer analysed the saliva of a girl suffer ing from a scorbutic affection of the mouth. There was a large secretion, forty ounces flow ing in the twenty-four hours. It was fetid and alkaline, and of specific gravity 1004.
Analysis yielded the following result : Water - - - - 988.8 Casein - - - - 645 Fat - - - - 0.6 Extractive matter and ptyalin 1.8 Carbonate of soda - - 1.2 Chloride of sodium - - 0.7 Phosphate of lime - Confervoid growths and infusoria were de tected in this saliva as taken fresh frorn the patient.
A specimen of saliva from a phthisical pa tient was examined by Landerer#, who found it to contain a great number of small fat glo bules aggregated into a viscid mass. These globules exhibited the properties of oleic acid.
Several kinds of diseased saliva have been analysed by Dr. Wright, and I shall subjoin his analyses.