son with these and not from blood of investigator's fingers.

This is already being done.

Questionable whether emulsion or bacteria can be controlled in either virulence or number, also whether technique can ever be made so practicable that it can be used except where there are extensive laboratories. At present the variance in the indices are as great for errors in technique which can not be controlled as the variance from disease, and until these errors can be controlled it is difficult to judge the field of usefulness of the opsonic index.

These uses are as follows:

To obtain the opsonic strength of certain sera.

It has been found that the opsonic index of serum diminishes rapidly if serum be kept even 24 hours. Hence it is thought that perhaps the reason antistreptococcus, antipneumococcus and other sera have not been successful in treatment, may be that these sera depend for their power on the opsonins they contain, and therefore their power is lost after serum is a few hours old.

Of course some sera do not depend on opsonic power but on bactericidal or antitoxic powers for their curative effects. Some do, however, and the strength of these may be discovered by the opsonic index.

Use in Diagnosis-Before this use can be advanced successfully, it is necessary to find whether opsonins are specific. That is, whether there is a specific opsonin for tuberculosis, one for typhoid, etc. If serum of typhoid gives same reaction to typhoid emulsion and tubercle emulsion, difficult to tell from index whether patient has typhoid or tuberculosis.

Variety of opinion as to whether opsonins are specific, but tendency is toward the conclusion that in some instances they are.

Much work has been done on the use of the opsonic index in diagnosis, especially in tuberculosis, and we will consider this disease as an example of the use of the index to determine whether disease is present, and the resistance of the body to it.

The opsonic index of normal blood under the present faulty technique varies from .75 to 1.2.

In tuberculosis it varies from .2 to 2, a large number of subjects falling within normal limits. In a case of doubtful diagnosis the following conclusions have sufficient foundation on experiment to be considered of value. 1. Persistently low index would point strongly toward tuberculosis.

2. Persistently normal would exclude tuberculosis. 3. Fluctuations in index from high to low would mean active process.

4. One examination of little value.

It has been found that body fluids near site of disease have lower index toward organism causing that disease than the blood serum of patient.

Therefore if fluid in chest of patient should show low tubercular index, tuberculosis could be inferred; if low pneumococcus index, lobar pneumonia could be inferred; if ascitic fluid of unknown origin should show low tubercular index, tuberculosis could be inferred.

Use of index as guide in building up immunity by

means of vaccines.

Very interesting work. If it can be perfected, presents great field of usefulness. Vaccines, that is, emulsions of dead bacteria, are injected in gradually increasing doses into patient sick with same disease, until resistance has been so built up by accustoming system to large doses of poison that it is able to take care of and throw off disease present.

When vaccine administered, first a period of lowered

resistance. This is followed by marked rise or positive phase, and this in turn by gradual decline, but as a rule resistance does not fall so low as was originally.

Failure heretofore, it is thought, has been due to fact that vaccines were not administered in correct dosage, or at correct time.

It is evident that if resistance is high, a too small dose can be given with no appreciable result, or if resistance is low, the primary fall caused by the same quantity of vaccine might be so great as to endanger patient's life.

In addition, if a series of inoculations be given, a second injection may be administered before recovery from negative phase of first, and so resistance be steadily depressed instead of increased. Constitutional symptoms have not been a sufficient guide, as to quantity or time of dosage, but with the index as a means of calculating resistance, it is hoped vaccines may be used more scientifically. The size of the initial dose must be measured accurately and the time for the administration of succeeding ones regulated. This time is just after the height of the initial rise has been reached.

Already some favorable results have been obtained in cases of staphylococcus, colon bacillus, and pneumococcus infections. In localized tubercular lesions Wright has also obtained good results, but in systemic infection not so favorable. The reason for failure in systemic infection is thought to be that the system has already so much poison to combat that it is extremely dangerous to increase this by vaccines.

Work has been done on the relative index between the serum of adults and children, between breast-fed and bottle-fed children, and between children of healthy and tubercular parentage. In no case, however, has it advanced beyond the experimental stage.

The more this subject is studied the more interesting

it becomes, and a worker may be over-enthusiastic in his conclusions.

That the discovery of opsonins is a valuable addition to science is an evident fact, but its uses clinically are as yet doubtful. The technique is still too faulty and the work on the application of the index in treatment and diagnosis as yet too limited for conclusions to be drawn, and if these uses are proved the skill necessary to put them in practice is too delicate for any except experienced workers in large laboratories.

In the meantime the clinician can only follow their work with interest, and wait until it is so perfected that it can be used by him to advantage.

TROPICAL APHTHA OR SPRUE IN GEORGIA.

H. F. HARRIS, M.D., ATLANTA, GA.

Tropical aphtha, or sprue, is a disease which was first described by Hillary in 1776, his observation on this affection having been made in the Antilles. Since that time the malady has been found in most of the tropical countries of the world, and even in some sub-tropical regions. As to whether the disease has been recognized in this country in the past, I am at a loss to say, as I have not had access to the literature.

My work on this subject extends back a number of years my first case having been seen in January, 1901. No report was made of this for the reason that the patient had previously to his illness lived for a time in the West Indies, and I was not absolutely sure, therefore, that the disease had its inception in this country. This case, with another, was reported in American Medicine for July, 1906. Since my report on these two instances of the disease several others have been seen, and I now take this opportunity of reciting to you the principal clinical features that characterized them, and to direct your attention to the fact that this very serious affection is not uncommon in our State, and, as it is only curable when a diagnosis is made early, its recognition becomes, therefore, a matter of great importance.

The clinical histories of these cases are as follows:

CASE NO. I. L. G. M., aged 32, white, male, a native of Georgia, a dental student, was first seen on January 15, 1901. His family history is negative, except that one sister has had an exactly similar disease to the one the patient complains of; this sister has always lived in Boston, Ga.