The elaborate treatise by Sanné of Paris on diphtheria contains a chapter entitled "Secondary Diphtheria." In it the author says, what all who are familiar with diphtheria will agree to, that secondary diphtheria does not differ in nature from the primary form, and that it exhibits a tendency "to occupy the organs which are themselves the seat of the more pronounced local determinations of the primitive malady.... Diphtheria is seen in the course or sequel of numerous diseases. Some appear to have a special proclivity for engendering diphtheria; these are specific maladies: measles, scarlet fever, pertussis." I have tabulated as follows Sanné's statistics of secondary diphtheria:

Diphtheria complicating measles,100 cases,83 deaths,15 cures,2 doubtful.
Diphtheria complicating scarlet fever,43 cases,22 deaths,17 cures,4 doubtful.
Diphtheria complicating pertussis,20 cases,12 deaths,6 cures,2 doubtful.
Diphtheria complicating typhoid fever,8 cases,8 deaths.
Diphtheria complicating tuberculosis,19 cases,19 deaths.

Sanné's statistics relating to the seat of scarlatinous diphtheria are as follows:

Fauces aloneattacked,15 cases.
Fauces with larynxattacked,4 cases.
Fauces with nasal fossaattacked,8 cases.
Fauces with larynx and nasal fossaattacked,4 cases.
Fauces with larynx and bronchiattacked,1 case.
Fauces with nasal fossa and lipsattacked,1 case.
Fauces with lips and skinattacked,1 case.
Fauces unaffected, 3 cases.
Diphtheria generalized, 2 cases.
Larynx only affected, 2 cases.
Nasal fossa affected, 1 case.

The opinion of so good an observer as Sanné, that when in scarlet fever, pseudo-membranous exudation appears upon the mucous surfaces which are the seat of scarlatinous inflammation, diphtheria has supervened, and not a croupous form of scarlatinous phlegmasia, carries with it great weight. That it was diphtheria in four instances in my practice I had sufficient proof, for this disease became dissociated from scarlet fever, and extended to other members of these families as idiopathic diphtheria.

Nevertheless, one of the most difficult problems which we have to deal with in certain cases is to distinguish diphtheritic from non-diphtheritic inflammation; and I see no reason why the scarlatinous inflammation when intense may not be sometimes membranous; and those no doubt err who ignore this, and consider every inflammation attended by a pellicular exudation diphtheritic. We know that in some cases of dysentery a fibrinous exudation occurs upon the surface of the colon; that in croupous pneumonia fibrin exudes into the bronchioles and alveoli of the lungs; and that physicians in localities where there is no diphtheria meet, though at long intervals, cases which they designate croupous pharyngitis and laryngitis; and it seems to me that the intense inflammation of anginose scarlatina probably sometimes produces the same exudation. Moreover, it is very difficult to distinguish in the swollen fauces between a membranous exudation and ulceration or superficial gangrene so common in malignant scarlet fever. The grayish-white surface, jagged and foul, may be the one or the other, an exudation or a sphacelus, and in certain instances it is impossible to discriminate between the two conditions at the bedside.

Diphtheria complicating scarlet fever sometimes begins nearly simultaneously with the latter. Henoch states that exceptionally he has observed suspicious patches upon the fauces before the appearance of the scarlatinous eruption upon the skin; and he adds: "I have had repeated opportunities of observing this unusual beginning. In such cases we must ask ourselves whether the first affection was really connected with the second, or whether the former was a true primary diphtheria, rapidly followed by scarlatina. This opinion is favored by the fact that I have only observed such cases in the hospital, in which infection with various forms of contagion can scarcely be avoided."

But usually it is not till the third or fourth day of scarlet fever that this complication begins. The patient has been progressing favorably with the scarlet fever, till on a certain day a marked aggravation of symptoms occurs. A higher temperature, more pungent heat, and the physiognomy of a more serious malady are present. On inspecting the fauces to discover the cause we observe a pellicle forming over the tonsils and perhaps other portions of the faucial surface. Often the entire aspect of the case changes by the occurrence of this complication, a mild case of scarlet fever becoming grave and fatal in consequence. Thus in a case which I saw with Dr. Hardy of New York the membranous inflammation of diphtheria, commencing upon the fauces on the third day of scarlet fever, extended to the Schneiderian membrane, and thence along the left lachrymal sac to the eyelids, producing redness and swelling along the side of the nose and upon the cheek like that of erysipelas. A thick diphtheritic pellicle occurred upon the under surface of each eyelid on the left side, with great tumefaction of both lids, gangrene of the cornea, and destruction of the eye. The case soon ended fatally.

The diphtheritic inflammation sometimes extends to the larynx and trachea, producing hoarseness and more or less obstruction to respiration. A thin film or flakes of fibrinous exudation, rendering the respiration noisy, developed on the laryngeal or tracheal surface, is, I think, not infrequent in diphtheria complicating scarlet fever, but the rapid development of a thick and firm pseudo-membrane, so as to imperil the life of the patient from the stenosis in the air-passages, has been much less frequent in my practice than it is in primary diphtheria and in diphtheria complicating measles or pertussis. The following were cases of this severe complication occurring in a recent epidemic in the New York Foundling Asylum. In these cases the respiration was noisy, but the obstruction to breathing seemed to be due to infiltration and swelling around the aperture of the glottis, rather than to diphtheritic croup, which the autopsies showed to be present.

Case 2.—A child aged three and a half years, who previously had symptoms of mild catarrhal croup, with moderate redness of the fauces, sickened with scarlet fever on Oct. 1, 1882, the rash being profuse and soon covering nearly the entire body. The axillary temperature was 103°, pulse 140; slight stridor in breathing and some cough; fauces very red, but free from membrane. Oct. 2d, restless, sleeping but little; has vomited four times. Oct. 3d, temp. 103.5°, pulse 120; fauces much swollen; still vomiting; rash abundant. 4 P.M., temp. 104.3°, pulse 128; tongue clean; some discharge from nares; urine not albuminous, but its quantity diminished. Oct. 4th, aspect that of very severe sickness; profuse discharge from nostrils; fauces of a deep red color, and a diphtheritic pellicle over tonsils and uvula; tumefaction along the sides of the neck; temp. 104°, pulse 140; breathing moderately stridulous; urine is passed more freely than yesterday; evening temp. 105°. Oct. 6th, croupy symptoms more marked; tonsils and uvula greatly swollen, so that the fauces are almost occluded; temp. 103.5°; breathing difficult, but apparently sufficient oxygen is received; profuse nasal discharge, and other symptoms as before. About 1.30 P.M. he was raised to take some milk, and suddenly became asphyxiated. His face was dusky, his eyes protruded, and he voided urine and feces. Dr. Swift, who attended the child, and to whom I am indebted for this history, immediately performed tracheotomy, which gave temporary relief by the expulsion of a considerable quantity of pseudo-membrane through the opening. On the following day the respiration again became obstructed at some point below the canula, so that it could not be removed; the features grew livid, and death occurred in convulsions twenty-six hours after the tracheotomy.