fact, all enzyme action is reversible. But not merely the metabolic changes as occurring in the living cell depend upon this reversible enzyme action, but, as a sequence, the action of drugs. Pharmacologic action can only be explained upon the basis of a chemic interchange between the drug and the living protoplasm by means of these substances. These agents which carry on the never-ceasing process of oxidation and reduction are known as oxydases and catalases, and they are so closely allied in regard to their action that, as Kastle has pointed out, it may be, after all, that when examined more closely the catalases will show peroxydase reaction. As it is, the two sets of substances, if they are really distinct, are certainly found in the closest and most intimate association in both the plant and animal tissues. According to Chodat, oxydases are ferments which influence the process of oxidation in the living cell either positively or

Petrograd, in 1899, discusses the nature and function of oxydase occurring in saliva, and Smith and MacDonald of Boston, in 1911, again refer to it in response to an inquiry by Dr. H. C. Ferris regarding the presence of a germicidal agent in saliva. As we intend to consider the biological significance of human saliva relative to its general ferment content in regard to dental caries in a later communication, we wish to reserve the discussion of this phase of the subject until then.

The various tests for maltase, catalase, and oxydase as employed for the purpose under consideration are discussed in the subsequent pages. As regards maltase, the various tests employed have been, in general, unsatisfactory owing to the very small amount of this ferment present in saliva. For the catalase test we have selected the permanganate method as giving most excellent results. It is based upon the equation:

negatively; in harmony with their specific function they are divided into oxygenases, i.e. bodies which take up molecular oxygen to build up peroxydases, and peroxydase which materially increase the stagnant peroxids present in dilute solutions.

Catalases may be looked upon, according to Herlitzka, as agents possessing the faculty of reducing peroxids and thereby acting as protectors of the living organism. Through the decomposition of hydrogen dioxid as resultant from the peroxydase action, into water and molecular (inactive) oxygen, the living cell is protected against the injurious effects of super-oxidation. Recent experiments carried out in the physiological laboratory of the University of Illinois which point to the fact that an increase or decrease in the amount of work, and hence in oxidation, in a muscle, is accompanied by a corresponding increase and decrease. in the amount of catalase, would seem to suggest that catalase may play a rôle in the oxidative processes of the body.

In his doctorate thesis, Slowtzow of

From the various tests which have been recommended for oxydase, we can vouch for good results obtained with the indophenol reaction (Röhmann-Spitzer). Smith and MacDonald claim that the color obtained with a freshly prepared 1 per cent. solution of pyrocatechin is a sufficient test for this enzyme in saliva.

TESTS FOR MALTASE.

Numerous tests for maltase are recommended in the various text-books. The minute quantities in which this ferment is present in saliva, and its frequent absence, eliminate certain tests completely, while others are applied only with difficulty. As maltase cannot be readily separated from amylase, the writer admits that in general the various tests for maltase in saliva have not been very satisfactory in his hands. The often-recommended reduction test with Barfoed's reagent for the above purposes has always failed. Polarization may be successfully employed, but rather copious quantities of the digested substratum are required,

and consequently large quantities of individual saliva. The degree of rotation of maltose hovers about (a) D, = 138°, while that of glucose equals about (a) D, 53°. As a test for the qualitative estimation of maltase the phenyl-hydrazin test can be recommended. This test is based upon the property possessed by certain sugars to form osazones, i.e. definite crystalline bodies which are typical for each sugar. Maltose-azone and glucose-azone may be obtained from saliva in the following manner: A test tube containing a mixture of 10 cc. of a 1 per cent. soluble starch solution and 1 cc. of saliva is placed in a water-bath of 38° for fifteen minutes. In the bottom of a small test tube, enough to fill its rounded portion only, an intimate dry mixture of two parts of phenyl-hydrazin hydrochlorid and three parts of sodium acetate by weight is placed, to which is added 5 cc. of the digested starch solution. The mixture is thoroughly shaken and heated in the boiling water-bath for at least 1 hours. The viscid sediment which is frequently formed at the beginning of the test should be filtered off at once. The tube is allowed to cool slowly in the water-bath, and the resultant crystals are examined microscopically. Typical crystals of maltose-azone are readily observed and occasionally crystals of glucose-azone may be seen; the latter indicate the presence of maltase.

One cc. of freshly secreted saliva is mixed with 5 cc. of 1 per cent. solution of hydrogen dioxid in an Erlenmeyer flask of about 50 cc. capacity, covered with a watch crystal and allowed to stand at room temperature, with frequent shaking, for two hours. Ten cc. of 21 per cent. sulfuric acid is now added, and the agitated mixture is at once carefully titrated with N/10 solution of potassium permanganate. At the appearance of the pink tint, which must remain unaltered for fifteen seconds, the titration is completed and the number of ce. used, read in one-tenth fractions, is noted. The control test, started simultaneously with the main test, consists of the same mixture, except that distilled water is substituted for the saliva. From 6 to 7 cc. of the permanganate solution is usually necessary to decompose the control test, H,O, solution. By compar ing the number of ec. of the permanganate solution required in the titration of the two tests a quotient is obtained which indicates the numerical power of the catalase present.

The problem involved in the catalase test may be stated as follows: How many cc. of N/10 KMnO, are required to decompose a mixture of a given quantity of a ferment plus hydrogen dioxid solution exposed within a given time to room temperature, as compared to the same quantity of hydrogen dioxid without the ferment employed as the standard test? The number of cc. of N/10 KMnO, required for the catalase test may be represented as CT, and that of the standard test as ST, while the assumed quantity of catalase which completely decomposes 100 cc. of 1 per cent. H2O, may be arbitrarily represented by 100, or as C(100). Consequently the formula for the catalase index reads:

which when subtracted from the catalase standard, i.e.

100 27.5 72.5;

the latter represents the quantity per cent. of the catalase present.

The above procedure furnishes excellent comparative results. If one is interested in the exact amount of hydrogen dioxid decomposed, a freshly standardized solution of potassium permanganate, containing 0.316 per cent. of the salt, should be employed; 1 cc. of this solution corresponds to 0.002 of hydrogen dioxid.

TEST FOR OXYDASE.

Required solutions: (1) Saliva.

(2) 1 per cent. alpha-naphthol sol-
ution.*

(3) 0.75 per cent. aqueous para-
phenylene-diamin solution.
(4) 1.7 per cent. sodium carbonate

solution.

One-half of one cc. of freshly secreted saliva is placed in a Petri dish 8.8 cm. in diameter, having a polished bottom. One cc. each of solutions 2, 3, and 4 are mixed in a graduated cylinder and diluted to 10 cc. with distilled water. Of this solution 5 cc. is added to the saliva, carefully mixed, covered, and allowed to stand at room temperature for one hour; then 5 cc. of 95 per cent. alcohol is added, theroughly mixed, and allowed to stand for one-half hour. The alcohol will dissolve the freshly formed indophenol. The mixture is filtered and compared colorimetrically with a standard color solution.

The standard test color solution is prepared by mixing 3 cc. of the undiluted alkaline alpha-naphthol para-phenylenediamin solution with 50 cc. of diluted

alcohol, i.e equal parts of 95 per cent. alcohol and distilled water, and allowing it to rest for about three to four days, or until the maximal color of indophenol has developed. As this solution

1 gram of alpha-naphthol is dissolved in 100 cc. of a mixture of equal parts of alcohol and water.

fades readily, it must be renewed as soon as a change in the intensity of color is noted, viz, in about two weeks. The color of indophenol is of a deep violet-blue. A more lasting test color solution which closely matches the indophenol solution may be made by adding diluted ferric chlorid solution to an aqueous solution of salicylic acid, or by using a very diluted solution of methyl-violet-B. In the absence of an expensive colorimeter a useful home-made apparatus for this purpose may be readily constructed according to the following directions: Ten small test tubes of the same diameter and size are placed in a test-tube rack and serially numbered. Tube 1 is filled with 10 cc. of the indophenol standard solution; tube 2 receives 9 cc. of the standard test color solution and 1 cc. diluted alcohol, and the remainder of the tubes are charged in the same manner with the geometrically diluted indophenol solution. By comparing the saliva-indophenol solution, placed in a test tube of the same size as that of the test solution, with the standard color solutions, against a sheet of white paper in a good light as a background, fairly reliable comparative results are obtained.

THE SUPPOSED SUGAR CONTENT OF

HUMAN SALIVA.

Blood, lymph, muscle, and other tissues of the human organism contain variable quantities of sugar. Normal human blood contains an average of from 0.06 varies within limits depending primarily to 0.11 per cent. of sugar. The quantity upon ingested foodstuffs. Under certain pathologic conditions, as in glycosuria, diabetes, uremic nephritis, etc., the quantity of sugar in the blood may be materially increased; as much as 1.11 per cent. has been recorded. The presence of sugar in the urine, especially under pathologic conditions, is so well known that it does not need to be especially emphasized. Basing our conception hypothetically upon these facts, it is, a priori, very alluring indeed to assume that sugar might be present in normal or in pathologic saliva, and that as a consequence this supposed sugar content may have

some possible bearing on the etiology of dental caries. Indeed, this conception is by no means new; numerous investigators, among whom especially Michaels and Kirk should be mentioned, have discussed this very problem. In a paper by Kirk, "A Reconsideration of the Etiology of Dental Caries, and a New Theory of Caries Susceptibility," published in the DENTAL COSMOS for January 1914, the following statement will be found:

In several communications, notably those already referred to as having been read before the Ohio State Dental Society in 1902 and before the Michigan State Society in 1913, I called attention to the probable existence of a fermentable carbohydrate substance in the saliva, the result of carbohy drate metabolism derived from the blood through the medium of the salivary glands. My attention was first directed to this matter in some studies of the saliva that I made in the laboratory with Joseph Porter Michaels in Paris in 1901. One of the routine tests made by Michaels in the examination of all specimens of saliva submitted to him was what he called the glycogen test, and I find in my notes made at the time that glycogen, according to Michaels, had been detected in the saliva by Salomon, and that other carbohydrate substances-for example, glucosehad been detected by Lecorché, Pavy, Lehmann, Jordeo, Nasse, Koch, and Gorup-Besanez, and that Arthus had determined the presence in the saliva of erythrodextrin, achroödextrin, and of maltose; and Michaels says: "I have myself determined the presence of sugar in the saliva of diabetics. Glucose takes a red coloration with Nessler's reagent, which passes into a grayish blue."

He says, further:

The difference of opinion relative to the passage of sugar into the saliva and the perspiration is explainable as follows: Sugar passes with difficulty into the saliva, and it is not apparent in appreciable quantities except in pronounced diabetics. The saliva contains large quantities of bacteria, and unless certain precautions are taken the contained sugar disappears by fermentation. The albuminous substances may interfere with the fermentation. According to Claude Bernard, cane sugar injected into the blood does not pass into the pathological saliva.

J. P. Michaels in his interesting brochure, "Sialo-semeiology," states that "There is a great divergence of opinion.

between authors in regard to the elimination of sugar through the sweat and saliva of diabetic patients," and enumerates these opinions as quoted by Kirk. In discussing the metabolism of diabetes mellitus, Von Noorden makes this statement:

Most researches upon the presence of sugar in the saliva have proved negative. Külz, however, quotes several observers who found it; and Fleck seder has recently reported two F. cases with a positive sugar reaction. Kraus, Jr., working in my laboratory, and using the most sensitive tests, including that of phenyl-hydrazin in each case, could find no trace of sugar in the saliva of ten severe cases who were excreting sugar in large quantities. Theoretically, one would think sugar ought to appear in the saliva sometimes, seeing that a dog's salivary glands let sugar through when 0.8 per cent. is present in the blood. Sugar values as high as this were obtained by transfusion with dextrose solution; they scarcely ever occur spontaneously in diabetes, but one would think patients would be found now and then whose salivary glands were abnormally permeable to sugar. In all researches upon the subject it is necessary to analyze the saliva fresh and pure, since reducing bodies may be derived from the decomposition of mucin. The sweet taste in the mouth that diabetic patients often complain of is probably not due to the presence of sugar, but to that of acetone.

To satisfy himself relative to the sugar content of saliva, the writer has utilized two very sensitive tests for this purpose, i.e. the micro-method of Ivar Bang, which allows a fair estimation of 0.02 mgm. in 100 cc. menstruum, and the micro-analysis of Bertrand as modified. by Michaelis and Rona. The latter method, while somewhat complicated, is especially to be recommended for the above purpose, as it allows an accurate determination of even the minutest quantities (less than 0.02 mgm.) of glucose. In no case, even in a saliva from a diabetic patient with a known sugar content of 7 per cent. in the urine, could the faintest trace be obtained. Basing his conception on experimental data, the writer must deny the presence of sugar in human normal or pathologic saliva. (To be continued.) 40TH AND SPRUCE STS.

I

T is my purpose today to present for your consideration some thoughts upon the condition of the children's teeth, and to give you an idea of the work that has been undertaken in this state by the "rural dental clinics" for the care of the children's teeth.

Vermont has the honor of establishing the first system of rural dental clinics in the country, and she may well feel proud of this fact, as it is recognized by the dental profession as the ideal method of procedure in the rural districts. The funds for the carrying out of this work were obtained through the generosity of Miss Emily Proctor and Hon. Redfield Proctor, who, realizing that the health of the child depends in a great measure upon the condition of the teeth, and appreciating the practical impossibility of the majority of the rural school children receiving dental treatment, established a fund for this purpose.

You are all more or less familiar with the plans for carrying out the work. In brief, it is to reach the rural districts that do not have access to a dentist, and to treat all of the children in these districts between the ages of six and twelve years who are in need of treatment, which will be practically all. This age limitation is made necessary on account of the large territory to be covered, and in view of the fact that the greatest amount of good can be accomplished between these ages.

EQUIPMENT FOR THE RURAL CLINIC.

A complete equipment consists of a car and a portable army dental unit,

which is capable of being set up in a short time and occupies a minimum amount of space. This unit can all be packed into a specially constructed box on the car, weighs about 500 pounds, and can be moved from one place to another with very little inconvenience.

This work will be done in the schoolhouses where possible, and will be consistent with the most advanced ideas of clinical dental pediatrics. The territory should be covered every six months, and will be after we have a sufficient number of men to make this possible.

While the operative procedures are very essential, the educational value of illustrated lectures, toothbrush drills, etc., is of prime importance. During these years a child's mind is very receptive and is capable of being molded and receiving impressions that would be lost upon the custom-hardened intellect of their elders. Therefore any correct hygienic principle instilled into their minds at this time will follow them through life, and will save them much suffering and disfigurement.

The physical examination of school children shows that from 95 to 99 per cent. are in need of immediate dental treatment, and the most conspicuous defect of the children is their unsanitary mouths. The children that have come under our observation average from eight to ten cavities each, usually accompanied by two or three broken-down, abscessed teeth which are continually pouring pus into the system and undermining the health of the child. Just consider for a moment what this condition meanseight or ten cavities ranging in size