170 THE NORTHERN MICROSCOPIST. 
manages with its 170 members to carry on an independent existence, has the 
nucleus of a library and cabinet of slides, possesses furniture and apparatus, 
holds demonstrating and mounting classes, organises sectional rambles for 
collecting raw material, insects, mosses, ferns, pond life, &c., and is in a 
remarkably good financial position. —ED. ] 
DONCASTER MICROSCOPICAL SOCIETY.—The twelfth ordinary 
meeting of the above society was held on Wednesday evening, the 18th May, 
the Rev. W. R. Weston (vice-president) in the chair. In the absence of Mr. J. 
B, Withington, two papers were read on the parasites infecting pork—one by 
Dr. J. Mitchell Wilson, on Z7ichina spiralis; the other by Mr. W. Walker, on 
Cysticercus cellulose. Asa large amount of interest throughout this and other 
countries has recently been manifested in the parasitical diseases affecting pork, 
which are capable of being communicated to man, the following points, alluded 
to by Dr. Wilson and Mr. Walker, may be of interest to general readers. The 
Trichina spiralis belongs to the group of round worms, and is most frequently 
observed enclosed ina cell or cyst, curled up in spiral shape. These cysts, 
which are found only among the muscles of the meat, are scarcely visible to the 
naked eye. Under the microscope, the worm in its free state measures in the 
female one-eighth of an inch in length, and the male only one-eighteenth of an 
inch. The young in each female has been estimated at from 10,000 to 15,000. 
Within two or three weeks after obtaining an entrance into the stomach, say 
from imperfectly cooked pork, these enormous numbers of young trichinze are 
born, and at once begin their wanderings. They burrow along the muscular 
tissues, becoming encysted, and it is during this stage that the violent muscular 
pains are experienced, which are prominent signs of the disease in man. Dr. 
Cobbold estimated that in one person, who had eaten a known quantity of pork 
infected with trichinze, there would be at least 42,000,000 parasites. Some of 
the epidemics which have occurred in Germany have caused a mortality of less 
than 2 per cent. of the persons attacked, while in 1865 an outbreak in one town 
attacked 350 persons, of whom too died. Dr. Wilson had carefully examined 
- eighteen specimens of pork, obtained from shops in different parts of his district, 
but in none of these were any trichinee found. Specimens were, however, 
shown, obtained from a friend at a distance, from a piece of ham infected with 
the parasites, and other prepared slides exhibited infected muscle both from man 
and the pig. It is said that a temperature of 160 deg. Fahr. kills the free 
trichinze, but the encapsuled worms are able to resist a much greater degree of 
heat, and are not destroyed by the usual methods of smoking, pickling, or 
roasting the meat. Ifthe interior of a piece of meat, roasted or boiled, retains 
much of the blood and colour of uncooked meat, the temperature has not been 
higher than 130 deg. Fahr. These facts ought to lead us to observe the advice 
of the medical officers to the Local Government Board, who say that any sample 
of meat, thought to contain the parasite, ought not on any account to be eaten, 
no matter how it is cooked, and that the only means of avoiding disease in man 
from the dangers arising from trichinee in meat from pigs is by very thorough 
and efficient cooking, which means generally cooking it one half as much again 
as the ordinary rule. At the conclusion of Dr. Wilson’s paper, Mr. William 
Walker, M.R.C.S., gave a short account of Cysticercus cellusos@, the larval form 
of the tapeworm, Zania solium. The presence of these parasites constitute 
that disease in the pig commonly known as the measles. Under the microscope 
they appear as small egg-shaped bodies lying between the muscular fibres. 
Although the larvze are found in other animals besides the pig, the mature tape 
worm exists only in man. The head of the Cysticercus is of globular form, 
furnished with four suckers round the margin, and fourteen or more hooklets in 
the centre. When the egg or germ of the tape worm is swallowed by an animal 
it is hatched in the stomach, and afterwards forces its way into the various 
tissues of the body, where, like the trichinz, it becomes encapsuled, and re- 
