The Berlin statistics (quoted from Braun, 1895, who takes them from the Berichte über die städtische Fleischbeschau in Berlin) are especially instructive; they are here reduced to percentages in order to bring out the results more prominently:

Number of organs of cattle, sheep, and hogs condemned for hydatids from 1888 to 1893. CATTLE (CALVES NOT INCLUDED).

1893-94 in all 13,424 lungs and 6,283 livers. (Berichte ü. d. städtische Vieh- u. Schlachthf.)

These statistics show that from 1888-89 to 1892-93 there has been a reduction in the number of organs condemned for hydatids both in cattle and sheep, which must be attributed to the system of abattoir inspection, and which must necessarily result in a corresponding decrease in hydatid disease in man. This reduction is not so apparent among hogs, but it must not be forgotten that Berlin slaughters large numbers of hogs imported from districts in which the slaughterhouse inspection is exceedingly superficial. We saw above that some German importations of hogs from Russian Poland, Bohemia, etc., were infected with Cysticercus cellulosae to 50 per cent, and hogs which are kept in such a manner as to allow this infection will certainly also bring up the German statistics of hydatids. I am strongly inclined to give much greater importance to the Berlin statistics than appears from the percentages of infection among the hogs.

THE ADULT TAPEWORM IN DOGS.

(See p. 101.) It seems to me entirely impracticable to attempt to guard against hydatid disease by trying to definitely diagnose the presence of the adult worms in dogs. If, however, the worm is found in

dogs, the latter should be killed and burned. The hydatid is altogether too dangerous a parasite in man to warrant a person's treating a dog which harbors Taenia echinococcus.

A decision of the "Professoren-Kollegium des Tierarznei-Instituts zu Brüssel,” though amusing to Americans, is of great importance to any country in which canine flesh is used as food; that is, that the oesophagus, stomach, and intestine of all slaughtered dogs are to be excluded from the market.

HYDATID DISEASE IN MAN.

It is important to consider this subject in this connection in order to insist upon the necessity of destroying hydatids found at abattoirs. Hydatid disease is the most fatal zoo-parasitic disease which affects man, "50 per cent of the cases dying within five years after infection," but its occurrence in man is fortunately comparatively rare in this country. One of the volunteer assistants in the Bureau, Dr. H. O. Sommer (1895-96), has recently compiled 100 cases which have been found in the United States. Many of the cases were among foreigners, and some of these were certainly infested before coming to this country. The 100 cases in the United States were distributed as follows:

Of 981 cases from various parts of the world, the greatest number occurred in persons between 21 and 40 years of age, as shown by the following classification by ages:

In man the organs most frequently infested are the liver, lungs, kidneys, and cranial cavity. Thus, of 1,806 cases of organ infections, the liver was infested in 1,011 cases, lungs in 147, kidneys in 126, and cranial cavity in 95.

Hydatid disease is especially common in Iceland and Australia. For Iceland the statistics are very contradictory, some authors estimating that 2 per cent, others 163 per cent (probably exaggerated), of the inhabitants are infested. Three thousand cases are reported for Australia between 1861 and 1882.

In central Europe the hydatid is found on an average once in every 130 post-mortems. The frequency varies in different localities, Mecklenburg and Pomerania leading the list. Ostertag gives the following statistics:

Peiper collected 150 cases for Vorpommern from 1860 to 1890; in postmortems at the Pathological Institute of Greifswald the percentage was 1.9.

Prevention of the disease in man.-The disease may be prevented in three ways

(1) By recalling that the dog is not a human being and should not be treated as one. Too intimate association with dogs is sure to breed the disease in man.

(2) By preventing infection among dogs. This can be done by keeping dogs away from slaughterhouses, and by the destruction (by heat) of all hydatids found in slaughtered animals. The slaughterhouse is the best place to institute measures against hydatid disease in man. (3) By killing all stray and ownerless dogs.

Adult Tapeworms of Cattle and Sheep (Subfamily Anoplocephalinae).

Adult tapeworms are more or less frequently found in the intestines of cattle and sheep, more rarely in the bile duct of sheep. As stated on page 68, they all belong to the subfamily Anoplocephalinae; they are very closely related to the tapeworms of horses, hares, and rabbits, and yet are entirely distinct from these forms.

Owing to many misidentifications of tapeworms which have been published, and to the meagre descriptions of some of the species, it is impossible to state exactly how many different forms actually occur in cattle and sheep, but we are now in a position to clearly define the most common forms which occur, especially those which are found in this country, and to suppress some of the worms which have been

described as distinct species of parasites in these animals, but which in reality are identical with forms previously described under other names, or are parasites erroneously attributed to these hosts.

FIG. 114.-Dorsal view of gravid segments of the Flat Moniezia (Moniezia planissima), showing the uterus, enlarged. (After Stiles & Hassall, 1893, Pl. II, fig. 5.)

Cattle.-Eight different species of tapeworm have been reported from cattle, but in all probability only four of them are found in this host; these four species all belong to the genus Moniezia, and two of them, namely, Moniezia planissima and M. expansa, are found in this country.

This Bureau has knowledge of only two adult tapeworms in American cattle, but I have examined specimens of three other species, namely, Moniezia alba, M. Benedeni, and M. denticulata, preserved in various European collections and bearing the label that they were taken from cattle. Of these three forms, M. denticulata (=Cittotaenia denticulata) is unquestionably a parasite of rabbits instead of cattle (Stiles & Hassall, 1896), and an error must have been made in the original label; M. alba and M. Benedeni are evidently legitimate cattle parasites. Rivolta (1878) states that he examined a tapeworm collected by Perroncito front the ox which he (Rivolta) considered identical with a worm he at first labeled "Taenia denticulata (?)" and which he later described as Taenia ovilla (=Thysanosoma Giardi). Perroncito has, however, recently stated to Lungewitz (1895, p. 6) that he found this worm only in sheep. Thysanosoma Giardi is accordingly not yet established as a bovine parasite. Von Linstow (1889, p. 20) includes two other tapeworms, namely, Stilesia centripunctata and S. globipunctata, as parasites of cattle, but I am unable to find the authority for this statement.

Sheep.-A large number of tapeworms have been described or recorded as parasites of sheep, but the number of species must be considerably reduced, for some of the forms described as distinct species are identical with forms previously described under other names, while other forms were misdetermined. Four species, namely, Moniezia planissima, M. expansa, M. trigonophora, and Thysanosoma actinioides, are known to occur in American sheep.

Several other forms, namely, Moniezia alba, M. Benedeni, M. Neumanni, M. nullicollis, M. Vogti, Thysanosoma Giardi, Stilesia centripunctata, and S. globipunctata, occur in sheep in other countries. Moniezia denticulata (=Cittotaenia denticulata) of the rabbit has erroneously been reported from sheep in Europe.

FIG. 115.-Egg of the Flat Moniezia (Moniezia planissima), greatly enlarged. (After Stiles & Hassall, 1893, Pl. II, fig. 6.)

Swine.-No species of adult tapeworm is positively known to be a normal parasite in swine, but Cholodkowsky (1894, pp. 552–554) records

specimens of Thysanosoma Giardi said to have been taken from hogs in Russia, and Detmers (1879), and Stiles (1895, pp. 220-222) have recorded three cases of other forms alleged to have occurred in this country.

The three genera of adult tapeworms for us to consider in connection with cattle, sheep, and swine are Moniezia, Thysanosoma, and Stilesia.

For a technical discussion of these genera and their species, with bibliographies, see Stiles & Hassall (1893) and Stiles (1896). For convenience of discussion, all of the forms will be treated together. For anatomical characters, compare figs. 111-124 with the key, page 21.

GENUS MONIEZIA.

It is often quite difficult to distinguish between the different forms, as the specific characters must to a great extent be taken from the internal anatomy, and it is therefore necessary to make a microscopic examination of one or more specimens which have been artificially stained. In many cases, however, these characters may be recognized if a fresh worm is allowed to macerate one or two days in water; then by pressing some of the segments between two pieces of glass and holding them to the light some of the internal anatomy can be recognized.

24. The White Moniezia (Moniezia alba) of Cattle and Sheep.

SYNONYMY.-Taenia alba Perroncito, 1879; Moniezia alba (Perroncito) R. Blanchard, 1891; (?) M. alba var. dubia Moniez, 1891.

This

This tapeworm has been recorded for France, Italy, and Algeria, but not as yet for this country. Poorly preserved specimens of M. planissima resemble this form in that the interproglottidal glands can not be seen distinctly. renders it possible that M. alba is simply a poorly preserved M. planissima-a point which can not, however, be demonstrated by a comparison of the original types; on this account, it is necessary to retain both species.

25. Vogt's Moniezia (Moniezia Vogti) of Sheep. SYNONYMY.-Taenia Fogti Moniez, 1879; Anoplocephala Vogti (Moniez) Moniez, 1891; Moniezia Vogti (Moniez) Stiles & Hassall, 1896.

Very little is known about this supposed species, which may be a distinct form or may be a dwarfed specimen of some other species. It has been found once in France and once in England, but is not yet recorded for America.

26. The Flat Moniezia (Moniezia planissima) of Cattle
and Sheep.
[Figs. 111-115.]

SYNONYMY.-Moniezia planissima Stiles & Hassall, 1892;
Taenia (Moniezia) planissima (Stiles & Hassall) Braun, 1895;
T. expansa pro parte of various authors.

FIG. 116.-Portions of an adult specimen of the Broad Moniezia (Moniezia expansa), natural size. (After Stiles & Hassall, 1893, Pl. VI, fig. 1.)

This seems to be the most common adult tapeworm in American cattle; it also