1881. ] Zology. 739 
counted upon an immunity from the ordinary evils of childhood 
in these animals. It is probable that the larger proportion of, in- 
deed most, young turtles when hatched survive, and when two or 
three years old, are fitted to resist successfully ordinary fish and 
avian enemies. They are not exposed to vicissitudes of weather ; 
the fact that the period of egg-laying (in New England from June 
10-20) is so constant, and varies so little at different seasons, 
shows that they are hardy and tough. Finally, the persistence of 
the type of gigantic tortoises on the Galapagos islands, indicate 
the wonderful vitality of this type of life in resisting prolonged 
climatic-and geological changes.—A. S. Packard, Fr. 
Tue TRICHINA AND OTHER ANIMAL ParasiTEs.—Renewed at- 
tention has been drawn to the Trichina. According to the Penn 
Monthly, Dr. Leidy has recently stated that this parasite was first 
discovered by an English surgeon in 1833, but its presence in 
pork was first detected by Dr. Leidy himself in 1840. He re- 
minds the public for their comfort: Ist, that all food animals are 
liable to have parasites, and that the tape-worm is sometimes con- 
veyed in rare beef; 2d, that only one hog in about ten thousand 
is infected with trichinz ; and, 3d, that thorough cooking will kill 
all such parasites, while none of them are poisonous after a good 
cooking. He believes that the Mosaic prohibition of pork was 
due to the danger of trichinosis, in a country where fuel was 
Scanty, and, therefore, their food seldom well cooked. He thinks 
that millions may have died of trichinosis in the centuries before 
the true source of the danger was discovered, and that many of 
the deaths which occurred in the army during the Civil War were 
due to the frequent use of raw and badly cooked pork, although 
ascribed to typhoid, rheumatic or malarial fevers. 
For a general account of the trichina and allied parasites we 
would refer the reader to an excellent book’ published a few years 
ago by Professor Van Beneden, a Belgian naturalist, who, by the — 
way, was the first to discover the history of the transformations of | 
the tape-worm. Van Beneden divides animal parasites into several — 
categories. The first are free messmates, which only live as board- 
ers or commensals in the bodies or in intimate relations with other 
‘@ certain louse of the dog, which harbors a larval tenia; and 
lastly parasites, which. include leeches, lice, fleas, ticks, ichneumon 
flies, and finally the genuine parasites, such as the tape-worm and 
trichina, which migrate from one host to another in order to com- 
plete their metamorphoses. It is the cheapest, most reliable and 
best illustrated work of the kind we have seen. 
‘Animal Parasites and Messmates. By Professor P. J. Van gages these 83 
illustrations, The International Scientific Series. New York: ppleton & 
* 1876. 12mo, pp. 274. 
