with dark knobs or linear processes (see Fig. 49, which shows the appearance of an artificial culture on gelatin x 3). When grown in milk it coagulates the milk. If the inoculated milk be kept for two days in the incubator at 35° this distinguishes it from the streptococcus of foot and mouth disease, to which it has otherwise remarkable resemblance. Some of the elements may be as diplococci or as short chains. Cultivated in broth it forms long and

exquisite chains (see Fig. 50, which is from a photograph of a subculture in broth). The elements of the chain are a little larger than those of foot and mouth disease.

Subcultures of the micrococci have the property when inoculated into calves of producing in them every manifestation of the Hendon disease, except sores on the teats and udders, and subcultures from human scarlatina inoculated into recently calved cows can produce in those cows, along with other manifestations of the Hendon disease, the characteristic ulcers on the teats-ulcers identical in character with those observed at the Hendon farm.

The post-mortem appearances of the chief organs affected are represented in Plate I. from Dr. Klein's original drawings. A is a section of the spleen of a cow which had been artificially inoculated with a culture of the streptococcus derived directly from human scarlatina. The gland was slightly enlarged, of a dark colour, and in the section numerous petechiæ are observed; B is a cut bronchial gland showing pigment and extravasated blood in

the cortical lymph sinuses and in the medulla; c is a portion of the lung showing numerous petechiæ.

The subcultures produce in rodents a disease pathologically similar to cow and human scarlatina.

Calves fed on subcultures established from human scarlatina obtain the Hendon disease.

Children (as proved by the Marylebone epidemic) fed on milk from cows suffering from the Hendon disease obtain scarlatina. The above, Dr. Buchanan 1 justly remarks, form a mass of evidence that the Hendon disease is a form occurring in the cow of the very disease that we call scarlatina when it occurs in the human subject.

So far the evidence of the Local Government Board's scientific staff; their conclusions are not, however, accepted in their entirety by all bacteriologists. In particular Professor Crookshank maintains that a disease in Wiltshire, apparently identical with the Hendon disease so far as external appearances go, is cow-pox, and infers that the Hendon disease was also cow-pox; to which Dr. Klein replies that there can be no question that the Wiltshire "is not the disease I saw at Hendon, and now known as cowscarlatina. Inasmuch as both are ulcerative diseases showing ulcers particularly on teats and udders, the two no doubt resemble each other. In so far as the ulcers have the structure of ulcers, the ulcers (if we may ignore considerations of duration) again have resemblances inter se. In so far as they are communicable from animal to animal, they are both of them infectious diseases. Also they both have micrococci in the discharges of the ulcers, though the micrococci differ in their characters. But there, it seems to me, the similarity ends."

Drs. Edington and Jamieson have also investigated scarlatina by biological methods. Edington, from his researches, ascribes the

true cause of scarlatina to a motile bacillus.

It is unfortunate that hitherto no eminent bacteriologist has either confirmed Klein's researches or any of the other rival theories. The last research of Klein, in which he has succeeded in reproducing the Hendon disease by inoculations of human scarlatinal matter in recently calved cows, is most important, and

1 Report by Dr. Klein on a Disease of Cows. Fifteenth Annual Report of the Local Government Board (Supplement), 1885-6. "The Morphology and Biology of Streptococcus," by Dr. Klein. Seventeenth Annual Report of the Local Government Board (Supplement), 1887-8.

could easily be tested. Taking the whole evidence together, it generally tends to prove that Klein's views are correct, but in such a complicated and difficult subject we must not too hastily accept them.

TYPHUS.

Typhus fever is peculiarly a disease of crowded poor centres of population. Hence it is specially Medical Officers of Health in charge of large towns who are likely to have an opportunity of seeing cases of typhus.

It is characterised by a high temperature, great muscular prostration, a distinctive eruption, is highly infectious, and one attack confers as a rule immunity against a second.

(297) Statistics.

The diminution of the number of deaths from typhus in modern times is remarkable. Before 1869 the Registrar-General included under one heading three classes of continued fever, but since that date there have been separate returns; 4,281 deaths from typhus were returned in 1869; with a few unimportant exceptions the deaths declined year by year to 318 in 1885; or, put in another way, the death-rate for typhus has declined from 193 per million in 1869 to 12 per million in 1885. In 1887 there were admitted into the Asylums Hospitals 36 cases; in 1888 only 1, and in 1889, 23 cases.

(298) Incubation Period.

There seems to be a real variation in the period of so-called latency. In 31 cases carefully observed by Murchison, in 1 case it was not less than 21 days; in 1 exactly 15 days; in 1 not less than 14 days; in 1 not less than 13 days; in 4 exactly 12 days; in 13 a period of 12 days was within the known limits; in 2 it was not more than 10 days; in 1 not more than 6 days; in 1 exactly 5 days; in 1 between 5 and 2 days; in 2 there was not more than 4 days; in 1 not more than 2 days; and in 2 there was no latent period, or only one of a few hours. From whence it may be gathered that 12 days is the most usual period, and that with regard to the question of quarantine a period of 15 days will take in nearly all the cases.